I think it really depends on how Lucky Deli translates food and food variety (if they are dim sum or Chinese food in other regions in China). For 角 is more on telling you the shape and texture of food. It is always harder outside, like deep-fried / pastry / fritter, with meat / veggies / sweet filling inside. But 餃 has many cooking methods, can be steamed 蒸餃, fried煎餃, deep-fried 炸餃. Very diverse in texture (from soft to crispy outside, with meat/veggies inside). Usually no sweet filling. Specifically in your case: 蝦餃, 海鮮餃, 韭菜餃 (all steamed for these examples) vs. 奶王角, 豆沙角 (deep-fired and sweet inside), 叉燒角 (pastry, savory and slightly sweet bbq pork inside)

Generally speaking, 餃 are steamed or boiled dumplings and 角 are deep fried.