In the following sentences (from duolingo):
그것은 그리 안 좋아요.
I used 별로 instead of 그리 and got wrong.
But I'm not sure what is the difference between them and when I should use one over the other. Both seem to mean the same thing (at least from my dictionary).
So when should I use 그리 over the 별로 and vice versa?