No, Rich has it about right. A documentary copy is an exact copy of the original with the original in hand. It has to be. It could be made new, but other than that, it's exact. A bench copy is a rifle made with the original in front of you. Everything is dead on for that particular rifle, not just the maker , but that rifle. You may have little variations in engraving, for example, so the maker can put a little of himself into it, but the style of the original remains. You might change the length of pull, the barrel weight or caliber, but not the style of the barrel. The bent trigger guard is now unbent, and so forth.
I have a couple of bench copies on my website that I'm proud of.