Coupon rate refers to the interest rate paid by the bond issuer periodically to the investor. Whereas, bond yield refers to the rate of return generated by the bond if any investor holds it till maturity. Major difference between the coupon rate and yield is that the first stays constant throughout the tenure of bonds while yield changes with factors such as remaining years for maturity, current price of bonds. To bond traders in the secondary market yield is important because yield-to-maturity determines profit or loss. On the other hand, investors who buys bonds directly from the company are concerned about the coupon rate.