"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.

Thank you Andrew and Su.Ki !

Sorry, I made a mistake. Not "tell A and B" but "tell A from B"

Following on from Andrew's answer: You can also use both these verbs with the preposition 'from' and they would have the same meaning. For example: 'Can you tell A from B?' = 'Can you distinguish A from B?'