couponA coupon is a piece of printed paper which allows you to pay less money than usual for a product, or to get it free. （打折或免费都可以，更倾向于优惠券）voucher A voucher is a ticket or piece of paper that can be used instead of money to pay for something. （更倾向于代金券） cash coupon和gift voucher 其实随便 还有一种说法，政府或单位发给员工福利的多用voucher，商家发放的多用coupon.北美人好像说coupon的比较多。
双双鱼儿
