"Tell A and B," does not really make sense if you are comparing it to 'distinguish.'
If you are comparing two sets of instructions from a textbook then you may find that on one stage it says "Can you tell A and B apart," and on another page it might say "Can you distinguish A from B."
These two questions mean exactly the same thing - " to distinguish," means to " to tell apart." Both thing mean to be able to identify the difference between A and B.
"To tell," (someone) something simply means to give them some information.