The sport is similar to its counterpart on ice, with some differences in moves, technique, and judging. Many ice skaters started in roller skating or vice versa. Famous champion ice skaters who once competed in roller skating include Brian Boitano, Tara Lipinski and Marina Kielmann. Artistic roller skating is often considered to be more difficult because ice allows the skater to draw a deep edge to push off from when performing jumps such as a Lutz or an Axel and roller skates are heavier than their ice equivalents, making jumping harder.