I'm a graduate student at a public university in the USA (Purdue University). They give me the choice of investing in either a 403(b) or a 457(b) plan. The university does not provide any matching funds. What's the difference between these, and on what basis should I choose one versus the other? What about when compared against a Roth IRA? My annual gross is around $14k.
Currently, I feel that I don't have enough income to choose both 457(b) and 403(b), but would putting money in both be a viable choice if I had a larger income?