Lovely painting! I just maybe think the castle could have been slightly more visible and stood out more, maybe? Or is that the point: its hidden in the forest? Anyway, I love the river curving down especially.
Sure - They both can do different things. For me ArtRage's oils are the best digital oil there is. However I have some custom brushes in Painter which I like to use too.
Both pieces of software can blend colours differently. I don't use Painter much these days it must be said, preferring ArtRage for most of what I used to use Painter for. However I still like what Painter does in some circumstances.
I have a couple of textured detail brushes in Painter which work really nicely so I chose to use them on this piece.