Are the trains in New York are the same or different ?

Not all NYC subway trains are the same size.

The same or different to... whay?

Same as or different from what?

They are not the same. Trains in New York or in any other railway companies, uses different types of trains. 
Other than new and old trains. They may use a specific type of train for routes that operates on a specific part of rail network. The reason might be because that part is not suitable for trains of a certain size. 

You should know that in Cars & Transportation, there is a Rail section.


That is where this should have been asked.

NYC subway trains come in 2 different widths. The IRT lines (now the numbered lines) were the earliest and were built to fit in narrow tunnels. The BMT and IND subway lines (now the lettered lines) had wider tunnels to accommodate wider cars that won't fit in the IRT tunnels. IRT cars on BMT lines don't get close enough to the station platform. Why weren't they built the same? They were owned by different private companies. The same is true of the other railroads in NY.  What is now Metro North was once the LIRR, the NY Central, the Pennsylvania, and the New York, New Haven & Hartford. Some of them have routes with no electric service.

Check out MTA.INFO for a map of the system./ 

It depends but they are very behind, in design, speed and safetiness than the trains in Europe and certainly Asia. 

Different like totally bro .