It depends. When meaning "unpolite" that would be "maleducado". Istead of saying that someone is "maleducado" you can say that he or she "no tiene educación" or "tiene mala educación". When you speak about something being rude, you say "de mala educación", for example, "it's rude to blow your nose at the table" would be "es de mala educación sonarse la nariz en la mesa". "¡Qué mala educación!" or "¡Qué poca educación!" would be "how rude!". When "rude" means that someone is using crude or offensive language towards someone, you can translate "rude" as "grosero". "Grosero" does not refer to impoliteness but to crudeness, impertinentness and/or offensiveness. "Borde" is used to mean crude, nasty and rude in a cocky way, when someone gets fresh and rude at the same time.

Alguna gente suele traducirlo como "maleducado" (unpolite), lo que no es erróneo, pero yo lo traduciría como "molesto" (de ser molesto, no de estarlo).

Maleducado, grosero.

Borde, grosero.