The long rail is actually an antenna.
It is used for the EAS system. EAS is the french short for Equipement à Agent Seul, which means “sole-agent equipment”. The antenna is used to transmit the video feeds of the platorm’s cameras to screens inside the driving cab.
The driver is able to remotely close or open the doors while watching for any incident, without the need for another agent. These antennas are used for Paris suburban trains (RER and Transilien), maybe for other trains as well.
Here is a picture with the onboard screens on the left :
The short one is called a “Crocodile”, as said in the other answer. The wikipedia page explains it better than me : https://en.wikipedia.org/wiki/Crocodile_(train_protection_system)
The short one is a so-called crocodile, a piece of safety equipment that transmits signals to the driver.
I’m not sure about the long one.
Credit:stackoverflow.com‘