Arsenal will find it easier to beat Inter than Barcelona. People still underestimate Barcelona a lot despite showing that they're a very formidable team. Barcelona plays high-risk football, but it's also high reward. They press you in your own half and choke you out, you have to rely on counters and Arsenal don't have the attack to rely on counters against Barcelona.

Anybody can win anybody, but don't make it seem like Barcelona is easier because if I was Arsenal, I'll prefer to face Inter than Barcelona.
You saw how Barcelona played Inter, they completely dominated. They most likely didn't prepare for the set pieces of Inter and they wee just unlucky to concede those kind of goals, especially in the first minute.
The second leg of that match is still a 50/50 game and I expect Barcelona to dominate but with crucial players missing, Inter stand a better chance.