Orange liqueur is essentially vodka sweetened with sugar and orange peels. There are many brands of this liqueur on the market, but the most common brands are Cointreau, Curaçao and Grand Marnier. For this margarita recipe I used Cointreau. It's the most commonly used, and best orange liqueur for margaritas. The other two brands are a little different despite their orange liqueur label. Cointreau is considered a triple sec liqueur due to its French origins and mix of sweet and bitter oranges. Curaçao comes from the Dutch Caribbean island of the same name and is considered both a brand and type of orange liqueur. Due to its tropical origins, the oranges for this liqueur are sweeter which is why its not considered a triple sec. Also, from France, Grand Marnier is considered a triple sec and Curaçao hybrid. Unlike the previous brands mentioned, its orange flavor is mixed with cognac.