Seals and Sea lions are two different families of pinnipeds.
From the Marine Mammal Center:
Earless Seals or True Seals
Phocids are sometimes referred to as earless seals or true seals and can easily be identified by looking at their ears and flippers. They have ear holes but no external ear flaps. They also have small front flippers and move on land by flopping along on their bellies. At sea, true seals move their rear flippers back and forth like a fish’s tail to propel themselves through the water.
Another family of pinnipeds are the otariids, sometimes referred to as eared seals. This family includes sea lions and fur seals. You can recognize these animals by their flippers and ears. Unlike true seals, they have external ear flaps. Their front flippers are large, and on land they are able to bring all four flippers underneath their bodies and walk on them. In the water, they swim using their front flippers like oars.
Along the California coast, you can find harbor seals and California Sea lions. The two seldom share the same stretch of beach. Harbor Seals are solitary and quiet. When hauled out on the beach, they lie next to each other without touching.
California Sea Lions are thigmotactic and much more vocal as they jostle for comfort and food.
Although the two groups do not usually cohabitate, at the Pacific Point in Sea World, you will find seals and sea lions sharing tanks. It is possible to buy a small paper container of anchovies to throw at the animals while you are standing around the tank, listening to the caretaker answering questions and telling you a little bit about the animals. On one visits, I saw a harbor seal standing upright in the water and imitating the noisy barking of the sea lions that were vying for attention so that the loitering tourists would through fish their way.
Unfortunately I can not find a picture of the sea lion wannabe, but he did get his share of the fish.