musical techniques
there's lots of musical techniques that you could refer to.
you should look at tempo, pitch, harmony, melody, texture, tone colour (what instruments), structure (verse choruse verse...., etc.). talk about the use of motifs, the main riff or hook. talk about the use of ritenuto - slowing down, accelerando - speeding up, crescendos - getting louder, decrescendos - getting softer (say whether they are gradual and stuff like that), accents, pauses.