With the best sweeping generality, there’s no such thing as acoustic foam. Marketing, Product Development, & Promotion are always going to repackage delicate, light-weight, fluffy, stupid-cheap packing foam for sale to the public.
Packing Foam’s job is to take up space in a box and above all, not weigh anything. Sound goes straight through it.
You would be shocked if you picked up a real piece of acoustic foam. It’s heavy, almost greasy, and you can’t easily glue it to a wall because it’s heavy enough to pull itself off. You will also be shocked at the cost.
One test you can do is put your foam on a picnic table outside. If the wind can blow it off, you didn’t get acoustic foam.
There are reasonable ways to do environment soundproofing cheaply. My favorite is furniture moving blankets. These are solid enough to keep two credenzas from smashing into each other in the back of a moving van.
I designed a “kitchen table sound studio” with some plastic pipes and two blankets.
I think the parts were $25 USD.
Koz