"Very sour fruit"
Translation:아주 신 과일
As far as I know—and I was explained the difference by native speakers, 아주 and 너무 means the same, which "too", but the first has a positive meaning, whereas the latter is negative.
너무 신 과일 — the fruit is sour and it is just over the top. 아주 신 과일 — it is good that ut is this sour.
Hope this makes sense to you.
That it true, but I think that it really depends on the case. In Korean, you can say 정말 신 과일 or 아주 신 과일 and it will still have the same meaning to people. If you want to be technical with dictionary definitions and grammatical issues, then they are different, but in this context there's really no difference. And, to be honest, most people don't use 아주 a lot. I think that 매우 would fit the phrase better.