@User: I would have called that the front end, but anyway. . . So Mohamed Shalan, who created the openlane "wrapper" (which is I guess the best way to describe it's relationship to OpenROAD), has his own set of scripts for driving the ABC logic optimizer (which is part of yosys but is its own tool, written by Alan Mischenko at UC Berkeley). I just use the default scripts that Claire Wolf put into yosys. Historically, at least, I have tended to work on smaller digital projects (more mixed-mode stuff than complete processors), so for me the default scripts for ABC are a "set and forget" thing. Anyway, it's the difference between those scripts that makes much of the difference in the gate count. The final gate count will also be affected by differences in the way that openlane does clock tree synthesis, fanout buffering, etc., vs. the way that qflow does them.