The actual raw forging might be equivalent to those done by other companies, but it's the machining and finishing of the raw forging that's the big difference.
What a company gets from the forging company is a lump of bare aluminum that looks vaguely like a part made out of clay. Some forging companies probably make forgings from different aluminum alloys, depending on what their customers ask for.
It's possible some forging companies forgings are more porous and may have small voids. These would have little effect on the finished parts usability, but it wouldn't be as high quality as a more uniform forging.
It's the alloy and the quality of the machining that turns a roughly shaped forging into a finished part.
"In general" when you have one finished part that costs significantly more than another, it's the alloy and the quality of machining and finishing that accounts for the higher price.
In other words, there's more to it then someone charging more just for their name.