QUICK ANSWER
"Must" is an auxiliary verb which is often translated as "deber", and "due to" is a phrase which is often translated as "debido a". Learn more about the difference between "must" and "due to" below.
must(
muhst
)An auxiliary verb, or helper verb, is a conjugated verb that comes before a main verb and determines the main verb's tense, mood, or aspect (e.g., I have gone.).
1. (obligation)
2. (suggestion)
3. (likelihood)
a. deber de
You must be very tired after your long drive.Debes de estar muy cansado después de manejar tanto.
A noun is a word referring to a person, animal, place, thing, feeling, or idea (e.g., man, dog, house).
a. no direct translation
This refers to an idiomatic word or phrase for which there is no word-for-word translation.
Having a cell phone is a must nowadays.Hoy en día es indispensable tener un celular.
This album is a must for all fans of jazz music.Este es un álbum que no deben perderse todos los aficionados a la música jazz.
due to(
du
tu
)A phrase is a group of words commonly used together (e.g., once upon a time).
1. (owing to)
2. (planned to)
a. previsto para
The building work is due to start next month.Las obras están previstas para empezar el mes que viene.