The biggest difference between Teriyaki meatballs and Swedish meatballs is the flavor profile. Teriyaki meatballs usually have a sweet, savory, and tangy flavor due to the addition of soy sauce, sake, and brown sugar in the marinade or glaze.  On the other hand, Swedish meatballs are usually flavored with white pepper, nutmeg, and allspice.  The Swedish meatballs also usually have a creamy sauce made with sour cream that is served on top.  Furthermore, Teriyaki meatballs are usually cooked in the oven or on a grill, whereas Swedish meatballs are typically pan-fried.  Both dishes make for delicious meals, but each has its own unique flavor combination.