how can u tell the diffrence between wht obd series u have ?

 

what do you mean as difference?

our cars came with obd0 (which really is pre-obd, but easier to say the former), and its not very sophistocated, which makes some things easier, some things harder.
then came obd1, which standardized some stuff, made it a little more complicated, but not too much. also, much easier to chip than odb0
then came odb2, which is extremely complicated, but easy to chip, i don't see why someone would convert their car to this.

 

the cars age if stock i dont really get what your asking

 

If you have a stock CRX its OBD0, if its an engine from 92-95 its OBD1, if its an engine from 96-current its OBD2. It also depends on who did the swap. In other words need more information.