You should not compare Coupons.com to Groupon. Different businesses. Groupon sells deals - you have to put money upfront i.e. commit to a discount. Coupons.com prints money in the form of %/$ off discounts. No need to commit any money even after you acquire a coupon from Coupons.com.
Coupons.com http://www.wellreadinvestor.com/companies/63241
Groupon http://www.wellreadinvestor.com/companies/10946