What’s the difference between futile and vain in the meaning of having no effect and result? Thank you.

Question

Answer

The expression is ‘in vain’

They are synonyms, so you can use either.

Personally I tend to use ‘in vain’ with a past action, and futile with a possible action.

I tried to call my friend but she was sleeping so it was in vain.

It’s futile trying to call my friend after 9pm any night as she always sleeps early.