Why are some teeth of a fetal pig pointed and other flat on top?

This is because pigs, as well as humans, are omnivores, meaning that they eat both plants and animals (meat). They use their sharp teeth to rip apart the meats, and use their "flatter" teeth, to chew up tougher things, such as plants.

Think of it like this: try thinking of trying to bite into a chicken wing with all "flatter" teeth... it would get pretty messy.

Then, try thinking of eating of things like celery, or carats, using just your "pointy" teeth... maybe your front teeth only. Think about how annoying long that would take you.

Pigs and humans could get along without both kinds of teeth... but it's simply for efficient to have both kinds.

GOOD LUCK!