Difference between 〜がち and 〜つい？


If both can express habits like things you tend to do, what is the difference
between their uses?

examples:

> イケメン*が通るとつい見ちゃう。
>
> 昔の話をしていると話がついつい長くなる。

Why was つい used here? Would 〜がち also make sense?




つい doesn't necessarily stand for habit but that you do something
unintentionally. がち stands for tendency and means that something is expected
to happen to some extent frequently, whether it's intentional or
unintentional.

