If you buy a pattern, you cannot copy the pattern and sell it. If you buy a fabric, you can't send it to spoonflower and have it duplicated and sell it. Both are violations of copyright.
Whatever you make with the pattern is yours to do with as you wish. You can sell it, give it away or throw it in the trash. The pattern or fabric maker can only copyright whatever they are providing, be it their pattern or the design of their fabric. Think of a pattern like a recipe for Green Soup. If the recipe is copyrighted, you cannot sell copies of the recipe, but you can make Green Soup all day long and sell it or take it to a potluck or just eat it.
In many cases, a maker will put a copyright mark on something and never actually get the copyright to discourage people from duplicating their work. It's not like a trademark, which you don't have to actually register. You just have to use a Trademark for it to be your property. A copyright has to be registered with the copyright office. It's not too expensive, but is paperwork intensive unless you hire a lawyer. So, that's an issue as well.
Most copyright infringement is about using someone's Trademark without buying a license. It's like making Dallas Cowboy T-shirts without paying the Cowboy organization to use the TM. Or, making a purse and calling it a Michael Kors purse and putting his name on it and selling it as a Michael Kors purse.
bkay