Defined Contribution Plan
These are individual tax deferred investment accounts funded by the employee. There is no guarantee of how much you will receive each month upon retirement. It is up to the employee to decide how much to invest and many accounts do poorly.
Defined Benefit Plan
A traditional plan usually administered by the state. The employee will no how much they receive upon retirement and the benefit is guaranteed. Professionals manage the account. **** NOTE***** This is the IMRF plan which you participate in.