couponA coupon is a piece of printed paper which allows you to pay less money than usual for a proct, 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,*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。
voucher
coupon