Raspbian vs. Raspbian Lite
Raspbian is an unofficial port of Debian for the Raspberry Pi. The port is necessary to make Debian compatible with the Raspberry Pi’s ArmHF (Arm Hard Float) architecture. Raspbian includes software for education, programming and general use.
Raspbian lite is a minimal version of Raspbian and omits things like Wolfram Alfa, Libre office, and most notably X server, the download clocks in at 300MB vs 1.3 GB for Raspbian and it’s ideal if you intend to run the Raspberry Pi as a headless server without a GUI.