ぜんぜん・あまり～ない: the difference
ぜんぜんN4
Meaning
(Not) at all
Past papers
Example
着物が全然似合わない。
Kimonos don't look good on me at all.
あまり～ないN4
Meaning
Not very, Not much, Not really, Hardly
Past papers
Tested once in past papers
Example
このケーキはあまり美味しくない。
This cake isn't very delicious.
How to tell them apart
「ぜんぜん～ない」: zero degree; fine in speech and writing.
「まったく～ない」: also zero, but more formal and stronger.
「あまり～ない」: 'not very'; only a partial negative.
When you see 「ぜんぜん」 in a question, look for 「ない／ありません」 after it.