Yeah that's how the two actors come across to me as well. Also the whole sensitive Sam thing always felt more like fanon than real canon. Sure Sam had moments like that and more of them in the first two seasons but so did Dean. :shrug:

Anyway, yeah I've always felt that Jensen made an effort give Dean a core of solid characterization and the writers followed along whereas HP was never able to do that even from the beginning, maybe partly because the plot was so focused on him that it drove his characterization rather than the other way around.