What is the difference between (ない)わけではない and (ない)ことはない?


As I understand, they are both very close in terms of meaning.

E.g.

> 私は歌を歌えない **わけではない** が、人前で歌うのは恥ずかしい。  
>  私は歌を歌えない **ことはない** が、人前で歌うのは恥ずかしい。

Both sentences would mean: "It's not that I cannot sing, it's just that I get
embarrassed in front of others."

I'm pretty sure there is a slight difference in nuance, that I can't quite
grasp yet.

Is it a matter of opposing the belief of someone that you can't? (while the
other is plainly a statement?)




There is very little difference, and they are interchangeable most of the
time. Still, I feel the speaker is more aware of the previous context when
わけではない is used. That is, a sentence using わけではない tends to have a nuance of
"that is not to say", "that doesn't mean" or "I'm not saying". ことはない is a
relatively "plain" double-negative sentence.




There is very little difference, and they are interchangeable most of the
time. Still, I feel the speaker is more aware of the previous context when
わけではない is used. That is, a sentence using わけではない tends to have a nuance of
"that is not to say", "that doesn't mean" or "I'm not saying". ことはない is a
relatively "plain" double-negative sentence.

