There are really just two differences:
 

1.	In a defined benefit plan, the employer bears the investment risk. This means that good returns lower the employer’s cost and bad returns increase it.  The employee’s benefit is not affected.  In a defined contribution plan, employees bear the investment risk.  Good returns increase their accounts and bad returns decrease them.  The employer’s cost is not affected.
2.	The IRS applies limits to both types of plans.  For a defined benefit plan, the limit applies to the benefit paid out.  For a defined contribution plan, the limit applies to the contribution going in.