When we make general application through how we know
how many bit compatable application like 16 bit,32 bit 64 bit
what is diff between the this type of application

mesu_me

In general, there is no reason with .NET to consider such a thing.

When the program is run, it is matched up with the .NET framework on the machine. That framework is the place where the capacity of the machine, and its design matters, and we don't write that part when we write .NET programs.