Inline skates have a wide variety of skates. Fitness and aggressive, both come under the same umbrella of inline skating. But they have some differences in their hardware according to their purpose.
For fitness skating, skates are made originally for the fitness training of ice hockey players. The basic purpose of skating is to keep your body in shape. Skates are the same in all aspects except the faster bearing, larger wheel size, and overall weight. The main focus is on the stability and comfort of your feet.
While when we talk about the aggressive skate, the whole focus is on grinds and jumps. Therefore they are made, keeping this in mind. Small wheels commonly have no conventional brakes and customized wheel alignments are common.