What is the difference between I must and I have to

[nq:1]" what is the difference between I must and I have to" ? Is it country dependant (ie it has a different meaning in UK , US, Australia, Canada...) ? thanks Colette[/nq]
No real difference in any of the countries referred to.

'Have got to' is considered unacceptable by some
but 'I've gotta go' is common.

[nq:1]" what is the difference between I must and I have to" ? Is it country dependant (ie it has a different meaning in UK , US, Australia, Canada...) ? thanks Colette[/nq]
There is no real difference between the two, except perhaps that "must" often expresses an obligation that comes from the speaker, while "have to" expresses an obligation imposed upon the speaker by someone or something el

The meaning is identical, but "Must" is a modal verb with some limitations.
One can put "have to" in past tense: "I had to" but "must" does not work that way: "I musted"??? It works in German though.

"Have to" is just a cheap replacement for a decaying verb in Britain and America.
See Grammar Playsheets:

Yes, Thomas is correct. For example, you have to stop at a red light (the obligation is imposed by the law). I must get my hair cut (the obligation is imposed by the speaker). And, of course, there is no "to" after the word must which many of my students say. It's a hard habit to break. So I tell them to use 'have to' all the time! lol Avoids the problem entirely.