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.
The crust of the Earth is of two distinctive types: Oceanic: 5 km (3 mi) to 10 km (6 mi) thick and composed primarily of denser, more mafic rocks, such as basalt, diabase, and gabbro. Continental: 30 km (20 mi) to 50 km (30 mi) thick and mostly composed of less dense, more felsic rocks, such as granite.