Rocks82, you missed a few points.
Ego will only take so many charges. Typically, you WILL trashcan it in 3-5 months.
BB will last indefinitely.
Ego will short out and die if fluid leaks into the battery connector. (this forum is full of such horror stories).
BB will not.
Ego will break if you drop it hard or smack it up against a particularly hard head.
BB... You can run over it with the family car. You MIGHT break the switch, maybe. If it's on concrete.
You are being too kind, Rock82. There really is no comparison.
No offense intended to the OP, but it's kind of a silly question. Kind of like asking what's the difference between Henckels and Ginsu knives.