A calque is a loan translation in which a foreign word or phrase has been translated literally into a native language. Flea market is a calque of the French marché aux puces (market of fleas). A loanword, on the other hand, is any foreign word assimilated into a native language. Kindergarten, café, bazaar, déjà vu, pasta, and crème brûlée are all loanwords or loan phrases.
Much to my entertainment, while loanword is a calque (of the German Lehnwort), calque is a loanword (from French).