Gibson

The only meaningful difference is the garnish: a Gibson is garnished with pickled cocktail onions instead of the olive or lemon twist used in a standard martini. Both drinks use the same gin and dry vermouth base. The pickled onion imparts a subtle savory, briny edge that distinguishes the Gibson's flavor profile.

Small pearl onions pickled in vinegar brine—often with a touch of sugar, mustard seed, and turmeric for color—are the traditional garnish. You can find pre-pickled cocktail onions at most liquor stores or specialty grocers. Some bartenders make their own to control the sweetness and acidity level.

The drink is popularly attributed to Charles Dana Gibson, the famed American illustrator of the Gibson Girl illustrations in the late 1800s and early 1900s. According to the common origin story, he asked a bartender at New York's Players Club to garnish his martini with a cocktail onion. The exact historical veracity is debated, but the name has stuck since the early 20th century.

The pickled onion already adds a mild briny quality, but you can add a splash of the onion pickling liquid to create a 'dirty Gibson' similar to how olive brine is used in a dirty martini. Most Gibson drinkers prefer it neat or with just the garnish, since the onion brine is sweeter and less salty than olive brine. The result is a more subtle savory note than a traditional dirty martini.