Full Definition of SITE. 1. a: the spatial location of an actual or planned structure or set of structures (as a building, town, or monuments) b: a space of ground occupied or to be occupied by a building.
Long story short - continental crust is thicker because is less dense, and it is less dense because it's composed mostly of quartz and feldspars, both having density around 2.6 g/cm3, whereas oceanic crust is made up by slightly denser Ca feldspar called plagioclase as well as pyroxenes and olivine, both having density above 3 g/dm3.
It can range from 25 km thick at the edges to 70 km thick near the center. The oceanic crust on the other hand is only about 7 km thick and considerably more dense. The crust and the uppermost part of the mantle make up the lithosphere, a solid region that is broken into plates. It is about 65 to 100 km thick.