I wouldnt really say he is a better attacking player.
From my perspective I think Milf puts Glenn into pretty good holes and creates a lot of half chances for him, but he gets dragged down 1-on-1 or the cover defence catch up to him.
I can recall a few times already this year where I thought if that was Fifi we definitely score simply because given half a gap fifi has the speed and strength to bust through tackles.
On the flip side Gillett, much like the rest of the right side, see precious little ball. You may be letting the dropped chance off Dearden sway your perception, but generally I think if given opportunities Gillett provides a decent conversion rate.
This year to date (both played 13 games):
Gillett - 4 tries, 0 try assists, 8 offloads, 1 line break and 1 line break assist
Glenn - 2 tries, 1 try assist, 4 offloads, 2 line breaks, 1 line break assist
They're both reasonably similar however 1 sits on the left with Milf inside and the sweeping play whilst the other sits on the right and has had Niko, Dearden, SOS and Turpin inside him and not a whole lot coming from Boyd to the right.