Lycan is short for the term Lycanthrope, which is a person who takes the form of a wolf, either through astrally or other means of changing/shifting. Lycanthropy is the study or changing of a lycanthrope. Lycanthropy deals with only wolves, yet it is misunderstood to deal with other creatures also.
Unlike Therians, a Lycan may inherit the wolf need to feed on a certain food type. Most lycans, tend to feed on raw meat. The type of meat depends on the type of wolf. A forest wolf may prefer small game while a valley wolf may prefer fish or duck, and a mountain fur may prefer small game that is hard to find like snow rabbits. If a creature is called a werepry than they are consider a half wolf half vamp, so they may feed upon blood and meat.
Therianthropy deals with many creatures. A therian is a person who has the personality of a creature yet does not change into that creature. A therian however may change on the astral plane but never change/shift any other way. Usually a therian is the same creature as the person?s spiritually creature.
Overall, a lycan is a type of therian, sort of like an upgrade therian. Lycans can shift many ways, while therians can only shift astrally or not at all.