A tremolo is a rapid alternation between two notes (or sets of notes, you can have polyphonic tremolos) which can be any arbitrary distance apart — including zero. A trill is a subset of tremolo, where the distance between any two notes being alternated is a second, either major or minor.
a tremolo is when you use your lower arm muscles to move a string instrument's bow very fast. in my orchestra music, the marking for tremolo is 3 short, 35 degree angle dashes that sit in between lines 2-4 on the treble clef. i'm not sure if the dashes can increase or decrease whether on how much the composer wants you to do tremolo.
a trill is usually have one finger down on a string and you move the next finger up and down quickly. this will create a series of 2 notes, the top being longer than the trill by a bit. trills are used to articulate notes to make them sound less plain.
Creativity and imagination. These skills would help for creating you own projects and artwork. It also would help with designs for your project and how you want to make it look like.
