Recently, I purchased two power tools from Craftsman - a 19.2v 1/2drill/driver and a 4.56A angle grinder that look exactly like ones sold by Porter Cable. I don't have links for the drills, but compare pictures of the two grinders below. Other than part of the plastic housing being a different color, you can clearly see that it's the exact same tool.
Most everything is made by one manufacturer different companies that order enough of anything can have there own branding on them the brands you have mentioned are at the lower end of the spectrum as for quality you will probably discover that the cheapest lithium ion cordless drill is just as good as the most expensive one on the market
Porter Cable Angle Grinder
Craftsman power tools are all made by someone else; Craftsman just puts their name on it. This is not uncommon in the tool business. Most Craftsman power tools are made by TTI based in Hong Kong, the same company that makes many Ryobi, Rigid, Taskforce, Rockwell, and Makita power tools. Porter Cable is a subsidiary of Stanley Black Decker which also owns DeWalt. In this case, I'd say Porter Cable makes the grinder and Craftsman sells a version of it.
