In my opinion they sound different, but my listening comparision is limited to the M22 on-wall vs. bookshelf. I find the bookshelf has a much smoother and even sound, whereas I've experienced some harshness with the on-wall at some upper frequencies that was unpleasant to my ears with some recordings. I didn't experience this with the bookshelf. I can't speak for the in/on wall, or the cabinet. The in/on wall should be an improvement and the cabinet should sound the same as the bookshelf version.
But, then again, others have registered no complaints with the on-wall speakers. It might be that I'm one of the rare individuals that have both.
