I was wondering what the difference between a tremolo and a trill was because when we had a tremolo in our music, my band teacher(a trombonist) just told us to trill the note. I looked it up online but the stuff I read did not make much sense.

A trill is usually from the written note to the note above it in the key you are playing. It's either a half step or whole step depending on the key and if it's specially annotated to be outside the key.

A tremolo is usually a minor third or more and the two notes for the tremolo are usually specified..

Joe B