Tag Question.

[zoobinshid]

Hello everyone,
Would you please tell me which is right and more common? and what is the difference between these two term because I have seen both of them?

1)Tag Question.
2)Question Tag.

Thanks in advance,

[Casiopea]

Why not both?
[1] tag question, i.e., what kind of question? The question ends in a tag; e.g. It's hot, isn't it?
[2] question tag, i.e., what kind of tag? the tag functions as a question; e.g., It's hot, isn't it.