The front lever can be though of as the opposite of the planche. It is basically the same but your now pulling instead of pushing.
Difficulty level is way up there with the planche.
The tuck front lever is to the lever, what the frog is to the planche. An easier starting position from which to build strength.
From the tuck, you can start to make it more difficult as you progress in your abilitys.
The gymnast legs are held wide as if in a split. This keeps the lever distance shorter, and makes the move easier than a full outstretched lever.