嗨~Justin!! Let me try this.. so if I set up the levels for those three words that you're confused with. It will be 1.客人 2. 顧客 3. 客戶(from daily life to the real business) . So 客人 is the regular one, also means guest. The level of 顧客 sounds higher than 客人, like if someone calls me 顧客 in a night market I would feel a bit strange, like it's a bit too polite and formal. Therefore, according to that, 客戶 is the most formal one, only use on the real business. About the VEGETARIAN, there is a shorter one, luckily yes!! Which is "吃素". But you'll have to add a subject before that. Like 我吃素, 他吃素, 他們吃素, 我們吃素。 So when you come to a restaurant you can ask this: 「請問你們有素食嗎？我吃素」 And they will probably ask you 全素 or 蛋奶素 or 鍋邊素( if you're a vegetarian then you'd know) Hope it's helpful and solve your concerns. Happy learning!! Alvin

顾客 in Chinese just focus on the coustmer who shopping in the store 客人 are more general than 顾客it can be instead of 顾客，but it can be discrible people who visit your house or company.sounds more polite than 顾客