There are many different types of jumps in figure skating1, and to the uninitiated spectator, they can all look more or less the same. This overview will not focus on what are known as 'dance' or 'positional jumps', which add flair to choreography, but instead on the 'rotational jumps' which more heavily contribute to scoring in competitive figure skating. Some of these jumps are more difficult than others, but none would be considered easy for the average person. After all, most people would have a hard time jumping off the ground and rotating around several times in the air, let alone doing it on the ice and landing cleanly!
The main differences between the jumps revolve around these factors:
The entrance edge, the edge the jump takes off from. In figure skating, 'edge' refers to whether the person is skating on the inside or outside edge of the blade. As a spectator, you can usually see this from which way the skater is leaning - if someone is skating on their right foot and leaning to the left, that is a right inside edge. Edges are further defined by being in the forward or backwards direction along the ice. The term 'free foot' is used in skating to refer to the foot not being used in the entrance edge.
Whether the jump is toe-assisted, using the toe pick (or toe rake) for the takeoff. Jumps that are not toe-assisted are also referred to as 'edge jumps'.
The direction of rotation for the jump, often described as being into or against the edge. For example, if a skater enters a jump on a right backwards inside edge, the skater was curving in a clockwise direction. So if the skater takes off from the right backwards inside edge and rotates counterclockwise in the jump, that would be turning against the edge. Jumps that turn into the edge are generally easier than jumps that go against the edge. Jumps that turn against the edge are also known as 'counter-revolution' jumps.
The number of rotations the jump has. For all jumps but the axel, a 'single' jump has one 360 degree rotation, a 'double' involves a 720 degree rotation, and so on. Unlike all of the other jumps, axels take off on a forward edge, and thus involve an additional 180 degrees - so a single axel uses a 540 degree rotation, and a double axel rotates 900 degrees before landing. For many of these jumps there are also half-rotation versions, such as the half flip.
The landing edge, the edge the jump lands on. Some jumps land on the same foot that was used for take off, and some do not.
The difficulty of a jump can be increased by the complexity of the footwork2 leading into the jump, but such footwork does not affect what the jump is called.
Jumps from a Backward Outside Edge
A counterclockwise jumper will enter these jumps from a right backward outside edge, landing on the same foot as the entrance edge:
The loop jump is an edge jump, taking off from the backwards outside edge, turning into the edge, and landing on the same edge.
The toe loop jump is a toe-assisted jump, in which the skater enters from a backwards outside edge, uses the toe pick of the free foot to help push the skater into the air, turns towards the toe pick and into the edge, and lands on the same edge as the entrance. It was also the first jump to be performed as a quadruple jump in competition3. Sports commentators will often simply refer to this jump as a 'double toe' or 'triple toe' when describing moves performed in competition. This is considered one of the easier jumps by many skaters.
A counterclockwise jumper will enter the next jump from a left backward outside edge, landing on the opposite foot as the entrance edge:
The lutz jump takes off from a backward outside edge, uses the toe pick of the free foot to jump into a rotation against the edge, and lands on the backward outside edge of the same foot used for the toe pick. It is generally considered the second most difficult of the jumps commonly performed in competition, and is the only one in which the skater rotates against the edge. It is not uncommon for skaters to turn the backward outside entry edge into an inside edge at the last moment - this makes the jump easier to complete, but is considered bad technique. Sports commentators and fans refer to such a move as a 'flutz', and it generally results in a reduction in score. The lutz jump is named after its originator, Alois Lutz, who first completed a single lutz in 1913.
A less commonly performed jump is the toeless lutz, which uses the same edges as the lutz, but without the toe pick assist. This jump is quite difficult to perform with more than one revolution, and is generally not seen in competition.
Since most jumps end in a right backward outside edge for counterclockwise jumpers, only jumps that take off from such an edge can generally be used as the second jump in a combination. This is why you will see a 'triple lutz, triple toe' in competition, but not a 'triple toe, triple lutz'. The exit edge of the first jump needs to move seamlessly into the entrance edge of the second, so most combination jumps end in either a loop or a toe loop.
Jumps from a Backward Inside Edge
A counterclockwise jumper will enter these from a left backward inside edge, and land on the opposite foot as the entrance edge:
The salchow jump4 is another edge jump, taking off from a backwards inside edge and landing on the backwards outside edge of the opposite foot. The salchow jump is named after Ulrich Salchow, who won 10 World Championships between 1901 and 1911; he completed the first single salchow jump in 1909. This is also one of the easier jumps, and the first quadruple jump landed by a woman at a competition was a quadruple salchow5.
The flip jump takes off from a backward inside edge, using the toe pick of the free foot, rotates away from the toe pick and into the edge, and lands on the backwards outside edge of the free foot. In some parts of the world, this jump is known as a toe salchow.
Two jumps no longer commonly observed in competition are the walley and the toe walley, both of which take off from a backward inside edge and rotate against the edge. A counterclockwise jumper would enter these jumps from the right backward inside edge, landing them on the right backward outside edge. The difference between them is that the toe walley is a toe-assisted jump and the walley is an edge jump.
Jumps from a Forward Edge
The only jump from a forward edge that's commonly seen in competitive figure skating is the axel; a counterclockwise jumper would enter the axel from a left forward outside edge, and land on a right backward outside edge.
The axel jump takes off on a forward outside edge, rotates into the edge, and then lands on the backward outside edge of the free foot. These are generally seen as the most difficult jumps in competitive figure skating. The axel jump is named after its originator as well - Axel Paulsen, who first completed the jump wearing speed skates.
A rarely seen jump is the inside axel, which takes off from a forward inside edge, and rotates against the edge.
Putting It All to Use
When you're first beginning to tell the difference between figure skating jumps, it can help to have a VCR or DVR, in order to be able to replay jumps in slow motion. Remember, the main things to focus on are the:
direction of rotation, and
number of rotations.