What's the difference?

what’s the difference between trials, freestyle, and street unicycling?

Ok ill do my best here.

Trials:
Clearing a group of obstacles(a line) as quickly and with the least amount of hops and dabs(feet touching ground) as possible. Use skills like SIF hops, Gaps, and Skinnies

Freestyle:
Alot like figure skating. You perform routines(ussually to music) and incorporate skills such as WW, Glides, Priouettes and Seat drags/pushes.

Street
Incorporates alot of the skills involved in trials and freestyle but witha a few that are Street specific such as aGrinds and Crankflips.

I hope that cleared it up a bit. Im sure that some one else will come along and give you a better explanation.

-Phil

I think of street and freestyle a little bit differently (your trials definition is fine):

Freestyle can either been in routines like you said (Individual, Pairs, Group) or Standard Skill, but also freestyle is technicqually any trick done using only the flatground. For example, crankflips and unispins are freestyle tricks but are usually used with obstacles to become street.

Street riding simply combines Street and Trials riding. It is usually very flowy (although there are static or stationary street tricks too).