Another specific case of Preterite vs Indefinite

[BlueSkies]

Hi,

In my exercise book there is a model answer which includes two seperate sentences I'd like to highlight:

"Mientras viajaba, hacía fotos."

And

"En su viaje aprendió much sobre la cultura de la gente"


In my own answer, I´d written: Mientras viajaba, aprendía mucho sobre la cultura de la gente"

Could anyone illustrate the distinction between the two variants, and tell me if my answer is incorrent?

Thank you.