余(あま)り～ないNot very, Not much, Not really, Hardly

なかなか and あまり～ない both express degree, but in opposite directions. なかなか implies exceeding expectations, e.g. なかなか美味しい ('It's quite tasty.'). In contrast, あまり～ない suggests a lesser degree, or falling short of expectations, e.g. あまり美味しくない ('It's not very tasty.').

たくさん is a noun meaning 'many' or 'a lot,' often used with verbs (e.g. たくさん食べた = 'I ate a lot'). To express the opposite idea ('not much' or 'not many'), the pattern あまり～ない is used (e.g. あまり食べなかった = 'I didn't eat much'). Note that あまり originally means 'excess' and can also appear in affirmative forms (see あまりに).

Both 別に〜ない and あまり〜ない are used to qualify negative statements, but differ in nuance. あまり〜ない expresses a lesser degree, e.g. あまり痛くない ('It doesn't hurt much.'). In contrast, 別に〜ない adds a tone of indifference or dismissal, e.g. 別に痛くない ('It's not like it hurts.', implying that there is no need to worry, etc.).

Both 全く～ない and あまり～ない express negation, but differ in degree. 全く～ない indicates a complete absence, e.g. 全く寒くない ('It's not cold at all.'). あまり～ない suggests a lesser degree, e.g. あまり寒くない ('It's not very cold.').

なかなか～ない and あまり～ない both express negation, but with different nuance. なかなか～ない implies difficulty or delay despite effort, e.g. なかなか話せない ('I can't speak easily.', implying difficulty despite effort). あまり～ない simply indicates a lower degree, e.g. あまり話せない ('I can't speak very much/well.').

Both めったに〜ない and あまり〜ない are used to qualify negative expressions, but differ in nuance. めったに〜ない means 'rarely' or 'almost never' and focuses on frequency, e.g. めったに行かない ('I rarely go.'). あまり〜ない is less strong, e.g. あまり行かない ('I don't go often.'). It can also qualify a degree or amount, e.g. あまり寒くない ('It's not very cold.'), while めったに cannot.

Both あまり～ない and すこしも～ない are used in negative statements, but differ in degree and tone. あまり～ない means 'not very (A)' and is fairly colloquial, e.g. あまり寒くない ('It's not very cold.'). すこしも～ない is more formal and emphatic, e.g. 少しも寒くない ('It's not the least bit cold.').

Both あまり～ない and そんなに express a negative degree, but with different nuance. あまり～ない means 'not very' in a general sense, e.g. あまり寒くない ('It's not very cold.'). そんなに (literally 'that much') can imply comparison to a standard and can be used with both negative and affirmative phrases, e.g. そんなに好きなら 'if you like [it] that much...' and そんなに好きじゃない ('I don't like it that much.').

あまり has the base meaning of 'excess', but its nuance changes with context. Together with a negative word in the form あまり～ない, it means 'not very (A)', e.g. あまり寒くない ('It's not very cold.'). Used affirmatively, it implies something of an excessive degree, e.g. 緊張のあまりうまくできなかった ('I was so nervous I couldn't do it well.').