hi 

please some one tell me  

what is diffrent between isomer and epimers ?

i should complete this answer

thanks 

This sounds like homework.  If you tell us what you have found out so far and where you are stuck, we can offer guidance.

 

We can offer hints so if you don't know where to start here is a hint

epimers are special types of isomers.

Here is the original example.

 

You should compare this with an example of otho, meta and para isomerism.

 

Note there are three of these but only two epimers.

 

Find out which of all these are optically active.