When there is friction, the skater starts off fast but slows down and does not get as high until finally coming to rest. This is because the force of friction acts against the skater's motion, converting some of the skater's kinetic energy into thermal energy and causing loss of speed and height over time.
When there is no friction, the skater starts off fast and maintains that same speed indefinitely. Without friction to oppose the motion, there are no external forces acting on the skater to reduce their speed or cause them to lose energy, allowing them to continue moving at the same velocity.