I have been planning my first electric project, doing lots of research.
I want to build an EDF airliner, most likely a 777. Most guys I see building EDF jets use foam for building them.
Would a foam airframe really end up being that much lighter than a balsa one?

I was hoping to get a plane that has about a 55" wingspan and using Wemotec 730 fans. Am I dreaming, would this be possible?

This electric stuff is pretty confusing, I hate feeling like a newbie again

Yes, I think foam is your best bet in this case. Balsa fuselages can be very light if the structure is relatively flat/square. Once you need all those complex/round curves of a scale fuse, the support structure/frame and skin (of balsa) will end up being heavier than foam. Bob

...unless you're going to do it like the old-timers or indoor duration types.

Once a model gets very big, foam does get heavier than balsa -- how light your building techniques are determines how small a plane that equal-weight cross-over happens at. The drawback is that leightweight wooden structures take a lot of work, both at drawing-board time and at building time.

Designing a lightweight round fuselage involves doing a very light truss frame inner structure, then adding formers and planking outside of that. (You have to lay up the outer skin by alternating sides as you add the planking so the stiffness of the skin doesn't warp the frame underneath.) If you make the curved outer surface the actual load bearing structure, the end product can be way lighter than you'd expect.