Freestyle skateboarding was considerably different from street skating in both style and equipment. For a start the skateboard itself was different - a freestyle board was longer and narrower than a standard skateboard. And then the main difference was the style. I suppose the best way to describe this to a non-skater would be to compare ballet and breakdancing - both acrobatic and sophisticated dances but completely different in their style. Freestyle was more based around performing balancing tricks and acrobatic manoeuvres usually using just the board (i.e. handstands on the board whilst rolling along) and street skating would be using whatever was in the street to perform tricks (i.e. railslide on a park bench).
At one time freestyle skating was commonplace but now it is comparatively unheard of with street and ramp skating taking the mainstream.