Games For Windows is a Microsoft label that requires games support a common set of standards, like widescreen monitors, the 360 controller if there's gamepad support, etc. This is a good thing.
GFW titles can be displayed in the Games For Windows shelf displays that you sometimes see in games stores, though not that often these days because Microsoft have to pay stores to use them (like all publishers have to do to get prominent displays of their games), and they prefer to spend their money promoting Xbox games instead.
GFWL is a completely separate online services platform that overlays on top of GFW. This is a bad thing due to the horrendous way it is implemented - it's a good idea in theory, but not in practice. See Steam for a good example of the practice.
Not every GFW title uses GFWL, but all GFWL titles will correspond to the GFW standards.
GFW titles can be displayed in the Games For Windows shelf displays that you sometimes see in games stores, though not that often these days because Microsoft have to pay stores to use them (like all publishers have to do to get prominent displays of their games), and they prefer to spend their money promoting Xbox games instead.
GFWL is a completely separate online services platform that overlays on top of GFW. This is a bad thing due to the horrendous way it is implemented - it's a good idea in theory, but not in practice. See Steam for a good example of the practice.
Not every GFW title uses GFWL, but all GFWL titles will correspond to the GFW standards.
