both pretty good, I think HD 7750 is a bit faster though? I have a ibuypower tower on the way with fx-4300 8gig and r7 240 can't wait lol might ditch the r7 240 eventually but not a bad budget card at all though.
The 250 is just, as victor said above, a rebranded 7750 with slightly higher clockrates. The cheaper card would be my suggestion as well. Both are decent budget gamers.