This fish doesn't have a lateral line. It also doesn't grow as long as the largemouth. And as you can tell by the name, it has a smaller mouth than Salmoides. Its mouth does not extend beyond the eyes. Salmoides prefers warmer, slower-moving waters like ponds and lakes.
Smallmouth bass are more common in cooler, faster-moving waters like streams and rivers.
Both are members of the sunfish family. Salmoides is a great game fish. That means people fish for him because he is good eating and puts up a good fight. Anglers, or people who fish, use live bait like worms to fish for Salmoides. Some people use artificial lures.