"No matter" vs "It doesn't matter"

What’s the difference between no matter and it doesn’t matter. I know the expression “No matter how hard…” but I have also heard “It doesn’t matter how hard” Is it correct? When do I have to use one or the other? Thank you a lot!

.
Offhand, I’d say that they are interchangeable, so long as you are careful to follow their different structures in a sentence.
.

Hi Anaojer,

To me ‘no matter’ sounds a little quaint or old fashioned. In another context suggesting the extremely popular ‘no problem’ expression, it can be used as a response to someone who apologises as in:

A: I’m very sorry I’m late.
B: No matter.

I would say that response does sound a little archaic and I think ‘It doesn’t matter’ would be more common or as I say, the ubiquitous ‘no matter’.

Alan

No matter:

SPOKEN 1.3
FICTION 5.3
NEWSPAPER 2.1
ACADEMIC 1.3
MISC 2.0

corpus.byu.edu/bnc/x.asp