Jambonneau is the traditional name in France. Elsewhere, butchers sell the same piece — or a close cousin — under a different name.
Both pork hock preparations from European tradition — Schweinshaxe is German-Bavarian roasted-with-crackling, jambonneau is French cured-and-cooked. Same anatomy, different traditions.
Same anatomical primal — jambonneau is the cured/cooked French version of the pork knuckle/hock. Different from German Schweinshaxe (roasted with crackling skin) and from fresh-jarret stew preparations.