Why are there two different types of scarves in the movies?

Probably something to do with different wardrobe designers. My guess is they were different in those film so designed different scarves and maybe the budget?

also they had different directors, and things on most of the films,

Personally, if I was (am) a student at Hogwarts, I don't think I'd want the same type of scarf. I'd like some variation, especially if it's a magic school.

I agree with the komentar above. The new wardrobe designers prolly didn't like the old scarves, atau just wanted to revamp the design. Personally, I prefer the alternating colors, and not the ones with lines. :|