These are currently - in 2018 - the newest trains of the Transilien regional train service around Paris. This train type is the SNCF's class Z50000 also known as "Francilien". They are in service since 2009. They were built by Bombardier and Crespin and they come in two versions: 94,3 metres and 112,5 metres long. Their maximum speed is 140 km/h.
Picture from Paris Gare St. Lazaire station 5.6.2018 by Ilkka Siissalo.

A very old Transilien electric multiple unit of the class ZA6400. These 25 kV AC old EMU trains were built 1976-79 by the companies Carel-Fouché-Languepin and Alsthom and modernised 1999-2005. In May 2018 there were still 53 trains out of an original number of 75 trains left. They have only been in use with Transilien = the regional TER service of the Île-de-France area around Paris.
Picture from Paris Gare St. Lazaire station 5.6.2018 by Ilkka Siissalo.

Another picture of the same old ZA6400 train.
Picture from Paris Gare St. Lazaire station 5.6.2018 by Ilkka Siissalo.

Side view of an old ZA6400 train.
Picture from Paris Gare St. Lazaire station 5.6.2018 by Ilkka Siissalo.

A very common train type in the Transilien service is the Z20500 double decker train. They were built by CIMT, ANF and Alsthom in 200 copies since 1988. It is also known as the Z2N train.
Picture from Paris Gare de Lyon 19.10.2017 by Ilkka Siissalo.

Closeup picture of the front of another Z20500 train of Transilien.
Picture from Paris Gare de Lyon 19.10.2017 by Ilkka Siissalo.

Another Z20500 train of Transilien.
Picture from Paris Gare de l´Est 20.10.2017 by Ilkka Siissalo.

This is actually not an electric motor unit train, so it should not be presented in this category, but since the other Transilien trains are here, we will make an exception to our own rules. So this is not an EMU, it is just a set of coaches, normally pulled or pushed by one of the Alstom Prima locomotives. These coach rakes are called VB2N. It stands for Voiture de banlieue à 2 niveaux, meaning just a rake of double decker coaches. They were built by CIMT and ANF 1974-84. Total number of coaches built was 589. They are used especially for the very long rush hour trains, just like here.
Picture from Paris Gare de Lyon 19.10.2017 by Ilkka Siissalo.

Just like in the picture above, this is also not a full EMU, but just a rake of coaches. These coaches are known as inox coaches, because originally they were not painted at all but just showed the grey colour of inox steel. They came in several varieties since 1963. This set in the picture is from the newest batch RIB76 (Rame Inox de Banlieue 1976). They were modernised and partly painted 2002-07 and Transilien stated they wanted to use still some of them until there are enough of the new Francilien trains (see above) available.
Picture from Paris Gare de l´Est 20.10.2017 by Ilkka Siissalo.

This train is of the class Z27500, better known as the AGC train. AGC stands for Autorail grande capacité, or a multiple unit of large capacity. These were built 2005-2010 by Bombardier. It is a very common regional train in all parts of France in the local TER train services, but there are not very many of them in Paris area Transilien service. They are available as three or four coach versions. Transilien only has the longer ones.
Picture from Paris Gare de l´Est 20.10.2017 by Ilkka Siissalo.

The RER trains are a strange mixture of "real" trains and metro trains. In and around Paris there are five RER train lines marked with letters A to E. There are two operators, SNCF Transilien and RATP and two electric systems, RATP's 1,5 kV DC and Transilien's 25 kV 50 Hz. RATP operates the RER lines A and B and Transilien the lines C, D and E. Electricity is always taken from an overhead catenary and some of the train models used can operate under both currency systems.
This train is RATP's class MI 84, also known as Z8400. It can operate with both 1,5 kV and 25 kV. 73 trains of this type were built 1989 to 1998.
Picture from the Paris Charles de Gaulle airport's RER station 21.10.2017 by Ilkka Siissalo.

RATP's class MI 09 double decker RER train seen from its side. These are really high capacity trains offering a very similar service than the Transilien trains do. This train model was built by Alstom since 2011 and it is only used on RER line A. Its maximum speed is 120 km/h.
Picture from Marne la Vallée station 19.10.2017 by Ilkka Siissalo.

Another view of the same MI 09 train.
Picture from Marne la Vallée station 19.10.2017 by Ilkka Siissalo.

A class Z5600 train of SNCF Transilien, but serving in RER traffic and now with a totally new livery of SNCF. It is a derivative of the VB2N coaches (See above how very similar they look!). They were built 1982 to 1985 and modernised 2009-2017. They are used not only in the RER traffic of Paris but also at Transilien and several other TER services such as the TER Bourgogne-Franche-Comté.
Picture from Gare d´Austerlitz 4.3.2014 by Ilkka Siissalo.

In 2018 locomotive pulled trains with coaches are getting more and more rare both in the regional train traffic (TER trains) as well as Intercité trains (InterCity).In many cases the old locomotives and coaches have been replaced by these new trains. This is an Alstom Coradia Polyvalent. It has both a diesel engine and the machinery of an electric multiple unit. This Coradia Polyvalent is working for GrandEst, that is, in the Intercity and TER traffic of eastern parts of France, including Alsace, Lorraine and so on. The Coradia Polyvalent trains can work under 1500V DC, 25 kV AC, with diesel fuel and versions for border crossing traffic also with 15 kV AC. Three, four or six coach versions are available. Train length is 56, 72 or 110 m and up to three trains can be connected together.
Picture from Paris Gare de l´Est station 5.6.2018 by Ilkka Siissalo.

Another Alstom Coradia Polyvalent.
Picture from Paris Gare de l´Est station 5.6.2018 by Ilkka Siissalo.

These totally new Bombardier Regio 2N double decker trains are intended for regional traffic with very frequents stops and lots of passengers. The model has been built by Bombardier since 2014. They come in 6,7,8 or 10 coach train variants which have a top speed of 200 km/h and are very fast in their acceleration capabilities. They are used by the different regional TER train services, such as here. This train belongs to the TER services of Hauts-de-France.
Picture from Paris St Lazaire station 5.6.2018 by Ilkka Siissalo.

Another Bombardier Regio 2N of Hauts-de-France TER services.
Picture from Paris St Lazaire station 5.6.2018 by Ilkka Siissalo.

The SNCF class X72500 railbus is a diesel multiple unit, which is intended for fairly long distances but for non-electrified lines with fairly few passengers. They operate longer distance TER and Intercites services, particularly in the areas south and west of Paris, the Paris to Laon line, around Tours, Nantes, Toulouse, Lyon, Dijon, Nevers, Grenoble, Bordeaux and the South Coast of France, but not in the north of the country. The model is a two coach railbus built by Alstom 1997-2002 in 117 copies. They have German MAN engines. Top speed is 160 km/h. Three two coach sets can be coupled to one train when needed.
Picture from Paris Gare d´Austerlitz 4.3.2014 by Ilkka Siissalo.

Another picture of the same X72500 railbus with its "mouth" open. This train belongs to the TER service of Region Centre.
Picture from Paris Gare d´Austerlitz 4.3.2014 by Ilkka Siissalo.

Two old SNCF railbuses of the class X2800 and one old express train coach in the middle, this train used to run the regional cross-border TER service from Besançon in France to La Chaux-de-Fonds in Switzerland. These X2800 series railbuses were built by two companies, Decauville and Renault between 1957 and 1962. They had one large MGO V 12 engine producing a modest power rating of 607 kW. Top speed was 120 km/h, for some units 140 km/h. This unit no X2827 had been built by Renault. All these trains were taken out of commercial use in 2009 and only a few museum units have survived.
Picture from Besançon 16.7.2007 by Ilkka Siissalo.

At the other end of the same TER train as shown above was this one, X2877. Also this individual had been built by Renault. During a hot summer day the personnel had to keep the engine roon doors open at all times. The huge MGO diesels created a hell of a noise and also tremendously heat inside.
Picture from Besançon 16.7.2007 by Ilkka Siissalo.

Two class Z9500 electric multiple units still in their original red and white TER livery. Later these same trains were repainted blue and grey. These class Z9500 trains were built 1982-83 for SNCF's TER services in Bourgogne, Franche-Comté and TER Rhône-Alpes. There were 20 of these trainsets alltogether. The train was designed to run both on 1,5 kV DC as well as 25 kV AC. Top speed was 160 km/h.
Picture from Besançon 16.7.2007 by Ilkka Siissalo.