It's not a matter of bells and whistles, the difference is: the efx is a Darth Vader helmet, the Hasbro BS is a parody of that helmet.
To us. To the average person who buys their prop replicas at Target, then it is a matter of bells and whistles. They're going to look at the BS and the EFX or whatever, think they both look like Vader, but the one has cool sound effects and the one does not, and the one that does not is 1/3 of the price. Again, I have a real vintage Graflex that I have done up as the ANH saber. My friends don't think it's as cool as my old oversized first run Master Replicas ForceFX lightsaber BECAUSE the ForceFX has lights and sounds while the Graflex is just a static prop that doesn't do anything.