What is the difference between あまり and そんなに? Are they always interchangable?


How do I use あまり and そんなに in negative sentences? It would be a great help if
it was explained with various examples of あまり vs そんなに.




**Update: as Chocolate-san pointed in the comment, this answer is wrong. I
didn't realize which part そんなに would apply to (probably thought of そんな). Not
sure if I have to remove it, please feel free to do so.**

* * *

Since you mention negative sentences specifically, it seems that you are
trying to translate into Japanese something like "It's not _that much_
interesting", and puzzling why そんなに doesn't fit.

In a negative sentence そんなに means _that much not X_ in a sense _not X beyond
expectation_ , while あんまり simply means _not much X_ , thus they are not
interchangeable. Consider the following dialogue:

A:「 **そんなに** [面白]{おもしろ}くない[映画]{えいが}を[観]{み}たいの？」- Do you want to see the movie
that is **that much** uninteresting?

B:「 **あんまり** [面白]{おもしろ}くないけど、[主人公]{しゅじんこう}はかっこいい」- Though it's not **that
much** interesting, the main character is cool.

Note that A evaluates the movie as a total waste and beyond (how a movie can
ever be that much uninteresting?), while B suggests that the movie may still
be somewhat interesting (though not that much interesting).




First of all, I don't think they mean exactly the same, there's a difference
not only in usage, but in the nuance it brings...

> あまり or あんまり - Much
>
> そんなに - That much, to that extent.

While あまり is used to simply state that you cannot perform something very well

I think that そんなに is kind of a "comparison", there is an established standard
to that action that you're supposed to perform, and you're stating that you
can or cannot perform it to that established point/extent.

Examples:

**あんまり:**

> その新しいゲームやったことある？ - Sono Atarashii Geemu Yatta koto aru? ( **have you already
> played that new game?** ).
>
> ごめん、ゲームのことは **あんまり** わからない。 - Gomen, Geemu no koto wa anmari wakaranai. (
> **Sorry, I don't understand much about games.** )

**そんなに:**

> ドイツ語で本が書けますか？ - Doitsugo de Hon ga kakemasu ka? ( **Can you write a book in
> German?** )
>
> もちろん、僕は書けないよ。僕はまだ **そんなに** 上手じゃないよ。 - Mochiron, Boku wa kakenai yo. Boku wa
> mada, sonna ni jouzu janai yo. ( **Of course I cannot write it. I'm still
> not that fluent.** )

