I've never found plywood in Cowboy. An occasional rock, but you get that in almost any lump (including RO). I did once get a piece of kiln insulation in Cowboy; I just removed it. Industrial scrap hardwood is just as useful as log hardwood; it is the same wood! And in fact, RO is cut into small pieces using saws just like Cowboy.
It's the process of making it into coal that is different. And that yields differences in the character of the burn. From my experience Cowboy lights quicker, and its initial burn phase is hotter... but it burns out more quickly. RO lights a bit slower, and does not yield as much of an initial heat blast.... but it burns more consistently, and yields greater heat over that time.
So I use both, for different purposes.
For smoking I fill my coal basket with RO. I then light a chimney of Cowboy, and dump that into a corner of the basket. That way my smoker gets hot more quickly AND it gets the benefit of RO's steady hot burn. I then toss chunks/sticks of whatever smokewood I want on top of the basket as the smoke progresses.
For grilling, I use Cowboy. Because that initial hot burn is exactly what I want to sear a steak or lamb chops or whatever.
What I do NOT use at all any more is briquettes. I have a half-bag of Kingsford sittin' in the garage, and a bag of some match-light stuff that my sis-inlaw gave me. I mmight over time use the Kingsford, but the matchlight is likely gonna get tossed. You think lump coal colors the taste of food? How about briquettes composed of some wood coal dust, some clay-chemical binders... and infused with enough propellant that you can put a match to it and it lights right up??