You start Death Egg standing rather than running in
Monitor changed to a spring
Shield was added here (it was an electric shield, by the way)
This annoying bumper thing was moved slightly to the right to make it easier to hit from the right side.
You appear behind the miniboss in the beta.
Right before starting Act 2, the pallete changes too soon.
Act 2 stays pretty much the same except for very minor changes like monitors and stuff.
After you beat the boss you get an egg prison unlike the final where you just run off to the right
Free the animals and it's off to...
Wait Domsday Zone? Well whatever let's go kick some ass!
..or not. Doomsday isn't complete yet, they just threw the boss's graphics in the background as placeholders. You just fall down and die.
Well what about the other Death Egg boss? They must have finished him right?
Wrong, same deal.