For me personally, I've never paid attention to the difference. But now that I think of it, I have to agree with Amy F. I pronounce "aisle" more like "eye-yul" and i'll has more of a quick transition from I to L (if that makes sense) It's very hard to explain but when i say "aisle", you'll feel yourself say 야 very quickly before going to the ai"sle" and with "i'll", your tongue just goes straight to the roof of your mouth, so i guess in hangul i would pronounce it as aisle (아이얄) and i'll (아일). It really depends on if people have an accent too. But this is the basic difference if people just have that standard american accent.

Unfortunately, I have to be the odd one out here. I say them differently. I say aisle as "eye-yul," but the way I pronounce "I'll" is closer to the way I pronounce "all." I can't explain it well, but if I pay attention to my mouth shape, it's almost the same as for "all" but my tongue lies flatter in my mouth. In fairness, this pronunciation difference *might* be one of the pronunciation habits I developed when singing in choir, when I was taught to get rid of as many diphthongs in my speech as I could. I honestly can't say whether most people I hear speak have this pronunciation difference, it's not something I've ever paid attention to.

I don't think there is. I'd pronounce 'I'll' the same as 'aisle' and 'isle'. You've got the same answer from English speakers on three continents now - so I think you can take that as a 'yes'.

I'd say them the exact same way: eye-yul

No, at least not for me in American English.