Can someone explain this with a bit more technical words?

So one of my friends is a music writer for bass guitar and he said “there’s two kind of tones that are pretty unique” then he mentioned Slayer and how they play then he mentioned Megadeth, which I kinda understood that one, but would be the technical word for those kind of “tones”. Because I wanna learn the bass like I’ve mentioned before, but I’m pretty sure I don’t wanna play standard tune. I wanna have a bit of a different sound.