Dxm (Robitussin CoughGels Question)

Just got a question

Is there any difference between a national brand and a store brand
at my local Eckerd DrugStore they got Robitussin CoughGels but for $2 cheaper they have a store brand Eckerd Tussin gel caps

on both of them the only active ingredient is Dextromethorpan HBr Usp 15mg

Would it matter if i got the store brand instead ?

As long as Dextromethorphan is the only active ingredient you can use it.

Yeah. When dealing with tussin, though, for me it seems like the generic brands skimp on the DXM because the trip seems weaker. Probably just me.