To me, the word chef is just a fancier kind of cook. When the word was first used at the beginning of the nineteenth century, though, it referred exclusively to the head of a restaurant, being a shortening of French chef de cuisine, which literally meant "head of the kitchen". Prior to that, chef was borrowed from the Old French word for "leader", chief, which is also the source of English chief (and Spanish jefe, meaning "boss, through Old Spanish xefe). That traces to Latin caput, which meant "head", but could figuratively be extended to leaders. Caput, through Proto-Italic kaput, eventually derives from a similar-sounding Proto-Indo-European word with the same definition. Usage of the word chef over time has gone steadily up since the 1980s, but the word chief seems to be getting less popular.
Adam Aleksic, a rising sophomore studying linguistics and government at Harvard University, has been described as the internet's sixth most famous etymologist. He also has disturbing interests in politics, vexillology, geography, board games, conlanging, and law.