How to Choose: 401(a) vs. 403(b)

[Sarah Harris]

My new employer has two options for Retirement Plans, both with Fidelity:

401(a):

-Employee after-tax contributions up to 60% of pay*

-Service-based match of 100% to 200% on after-tax contributions up to 3% 

-1% annual contribution

403(b) 

-Employee pre-tax and Roth (after-tax) deferrals up to 80% of pay (up to the annual IRS limit) 

-Catch-up contributions available to employees who are age 50+

I am not well-versed and only have experience in a 403(b) with a previous employer. Any recommendations on how to choose and/or insight on why choose one over the other?