Schnapps are a distilled liquor, often flavored heavily and have lots of sugar. Common flavors are peppermint, cinnamon, root beer, peach, apricot, apple, etc... Some cheaper spirits sold under the...
A martini is gin and dry vermouth. Assuming you mean a cocktail, I suppose you could make one maybe with a lot of gin, lemon juice, schnapps, and orange bitters. Good luck!