As Adrian said, the meaning of both verbs is the same. I'd only add that you can use „pytać się" to emphasize a specific fact or point in your expression. Furthermore, mind the fact that each of these verbs works with a different case. Pytam dziecko, czy lubi czekoladę. (pytać + Biernik) Pytam się dziecka, czy lubi czekoladę. (pytać się + Dopełniacz) I hope I could help.

Please, keep also in mind, that some people (like my Polish teacher at university e.g.) think that the expression "pytać się" is totally incorrect. I have done some research and I know now that it is correct but still in my opinion it is much safer ALWAYS to use "pytać" (someone not "się" = yourself)

Basically there is no difference between those two sentences and the sentences have the same meaning .