Blade is about the same size but the handle is not. Technically, the Dragonfly is one form factor greater than the Manbug, so they are hard to compare. The Manbug favors ultra-compact where as the Dragonfly favors "little big knife" performance. The Dragonfly is right about at the size in which most people will find they prefer using a pocket clip instead of just setting the knife in the pocket.
Also, the Dragonfly opens up to form an additional finger coil, as noted. This really gives excellent control for precision cutting and it's much more leverage than the Manbug. The blade shape of the Dragonfly is arguably better-suited to harder work, and while I've not broken the tip on either, I think the Dragonfly will have a much stronger tip. The Dragonfly is also very easy to sharpen and I think the high profile of the blade helps better control precision cutting. It is a bit wider when closed versus the Manbug, but it's still pretty compact.
While I know the Dragonfly is available in SuperBlue and ZDP-189 super steels (the Manbug probably is too), I think the base VG-10 steel is excellent and an excellent choice for a daily use knife (it's also a lot less expensive than the models with the super steels.) IIRC the Manbug is also standard in VG-10.