"Essen" vs. "fressen"
My understanding is that while "essen" CAN be applied to animals eating, "fressen" is strongly preferred.
"Fressen" can also be used to say someone is eating like an animal - eat like a pig
Genau. It's also used in these ways: "Etwas gefressen haben" = have understood something. "Jemanden gefressen haben" = hate somebody's guts. And my favorite: "Jemanden zum Fressen gern haben" = like somebody so much one could eat him/her.