BEANTWORTEN SIE FRAGEN - English

Must is an older way of saying almost the same thing. Must is much more formal.

Have to = Must
but we use must when we are talking about rules from the state: you mustn't smoke in the public buildings.
whereas we use "have to" When we are talking about obligation from a person like "mother ,father,friend..." for example: you have to do your homework now, or you'll failed.

when you use must it means you have a choice and you should choice the alternative that your contact says to you for example: you must eat your drugs
when you use have to it means you don't have the right to choice the other alternatives for example:
solders have polish their boot.