This may be a stupid question but here goes. They sell "Silicone Caulk" and "Silicone Sealant". What is the difference? Is it the same thing? They also sell "Kitchen and Bath Silicone Sealant" and "Doors and Windows Silicone Sealant". Again what is the difference? Are all these products truly different or the same thing?

I am trying to remove the multiple layers of paint from a spun aluminum roof exhaust fan, like the ones you see on commercial buildings everywhere. I am using Zinsser Strip-Fast power stripper, which claims to work on both latex and oil paints. After applying, I let it sit for 15 to 30 minutes, then hit it with a plastic scraper. It seems to work fairly well on the outer layers of paint, but not the bottom-most layer. In fact, that layer doesn't even seem to be affected by the stripper. It WILL come off if I use a green Scotchbrite pad, but this also scratches the aluminum badly. I do know that the fan was originally unpainted, so that stubborn bottom layer is not some sort of factory coating, yet it seems hard as rock. My plan is to restore it to the factory bare finish, without paint. If anyone has any ideas, I'd really appreciate it. Thanks, Andy