Learn English – What does “come out” mean in ” ‘I came out top in the test,’ he bragged”

"- the life out of me", usually "scared the life out of me", is an idiom. It loosely means "until I had no energy left". If something frustrates the life out of me, I am exhausted from being so frustrated and feel like I can't do anything else.

In your example, you can use either. I would say find out is a bit less formal.

There is a difference in meaning though, and in some cases the words are not interchangeable. You can only find out a fact, but you can discover anything that can be perceived.

For example:

I found out that I'm pregnant.

Did you find out whether it's going to rain tomorrow?

I discovered a $20 bill under a rock.

I discovered confidence in myself that I never thought I had.

There is a slightly different usage in to be found out, an idiomatic expression meaning to be exposed or caught.