Look everyone in the arms market sells they same shit. They just slap their logos on them and claim they made it. or make customers think they actually made the products by using various marketing strategies.
So to answer your question. The lowers are pretty much the SAME with just different logos on them but of course there is different types of firearms where lowers will be different in sizes and possible in shape.
There are basically two kinds of lowers, forged and billet. Forged mil-spec lowers from any manufacturer are all pretty much the same but with different logos. Billet lowers are more expensive and are really meant more for aesthetics. Forged lowers are a little stronger and can take more punishment but both will easily handle anything that most shooters are likely to put them through.