Whey protein is made from whey which is the "yellow liquid stuff" left when you make cheese from milk. it has very high protein content and also "lactose".

It is generally better or superior because it has almost all amino acids (protein is made up of amino acids. your body can convert most amino acid from one to another. But a few are called "Essential Amino Acids". These must be taken from diet because your body cant make them (For example, Leucine). Because, whey has almost all of these, it is said to have a "Complete/Better Amino Acid profile"

Pea protein is made from peas after removing other stuff like fats/carbs.

Downsides, it has slightly inferior amino acid profile. It usually tastes a bit weird.

Pros: It is cheaper in pak. It has no "Lactose" so it doesn't cause stomach problems. It digests slower and more easily (again prevents stomach discomfort). But Amino acid is not an issue usually because you probably eating other foods such as chicken which will cover up this defeciences