Difference between Stick it to someone and Stick to someone

stick it to someone —(sl.) treat smb. badly or unfairly (overcharge a person for services, etc.):

• I guess I looked as if I had a lot of money and they decided to really stick it to me.

stick to someone—

1. (also: stick with someone) remain loyal to a person; stay close (in the face of danger, etc.):

• Just stick to me and I’ll lead you out of here.

2. continue to use or employ a person:

• We finally decided to stick to our present supplier of ball bearings.