Some may assume that fleas and gnats are the same, but you should know that they are different from each other. Gnats are insects that can fly, whereas fleas cannot fly, but they would hop whenever they would need to move from one place to another. There are also some differences in terms of size, although there are times when their sizes are the same. For fleas, they are expected to grow up to 3.5 mm, but gnats can be longer.
The adult gnats can grow up to 15mm. If you would check closely, their appearance is also a bit different. You will notice that gnats will have wings and long legs while you can barely see the legs of fleas.