These large beeware manufacturers cut parts by the truckload. They don't buy a few clear boards, some with small tight knots, and some lousy ones.
It's most all #3 grade. At best when the boards are run thru the auto-fed rip saw the loader flips the worst side to the trim side. Then it goes thru the auto-feed chopsaw for length, next stacked for the finger joint cutter(they are not really dove-tails) or it might be a continuous fed double end cutter.
Basicly when all the operations are complete someone grades the parts. The perfect clear ones are seperated out to one stack and the ones with knot holes, loose knots, Large knots, knots in the fingers, large gouges, etc. go in the economy pile, the rest(most) are commercial grade.
So all the joints should fit the same, you just might need a little wood putty for the knot holes or let the bees fill the gaps.
I find the commercial grade from Dadants excellant value and durability.
goodluck