The difference between a zero-coupon bond and a regular bond is that a zero-coupon bond does not pay coupons, or interest payments, to the bondholder while a typical bond does make these interest payments. The holder of a zero-coupon bond only receives the face value of the bond at maturity. The holder of a coupon paying bond receives the face value of the bond at maturity but is also paid coupons over the life of the bond.
Zero-coupon bondholders gain on the difference between what they pay for the bond and the amount they will receive at maturity. Zero-coupon bonds are purchased at a large discount, known as deep discount, to the face value of the bond. A coupon-paying bond will initially trade near the price of its face value. In other words, a zero-coupon bond gains from the difference between the purchase price and the face value, while the coupon bond gains from the regular distribution of interest.