Expanding Foam

Looks like the £3.33 one is an aerosol can and the other is a gun to fit an aerosol to .Probably it's less messy using the gun rather than the plastic tube normally used with the aerosol .

As for reusing the stuff you need to buy gun cleaner as well. It's in aerosol form as well and smells like acetone .You spray it in to the applicator and also the end of the aerosol to get rid of the residue . Toolstation sell it as well

Stuart

(other than that, hard to tell as there is no picture that I can see for the cheaper one)

The can has a slightly more elaborate "nose" on it. You screw it onto the gun rather like a blowtorch canister. The valve and trigger mechanism is then contained in the gun and does not rely on the bendy rubber seal at the top of the can. The result ought to be more precises control of the application, and hopefully a can that reseals better if left part used and disconnected from the gun. Note you also need the can of gun cleaner otherwise you won't be getting any reuse out of that!

In article , VisionSet writes

You might find the info here of use: