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Plans qualified under Internal Revenue Code (IRC) Section 401(a), including pension, profit-sharing, stock bonus, and 401(k) plans are often referred to as "qualified" plans.
Simplified Employee Pensions Plan (SEP) are under IRC, Section 408(k).
At http://personal.fidelity.com/products/retirement/getstart/newacc/keogh.shtml.cvsr Fidelity has good basis information on both the SEP-IRA, 401(k) and self emploked 401(K) plans.
I hope this helps.