Most of your 1911 questions can be answered by a little Googling, but basically, most people, when they say 1911, are talking about a pistol based on the original John Moses Browning government model, that the military used as their main sidearm for several decades. They were made by a variety of manufacturers, but the parts were all interchangeable. That is also true of many of the 'improved' clones of the 1911 design, that are also manufactured by a variety of gun makers.
I, personally, like Springfields, because they are well made and the parts are interchangeable with the government model, making them easier to obtain, and maybe cheaper. Mine is a 'Commander' sized (Colt nomenclature), which simply means full size, but with a 4" barrel, instead of the standard 5." There is also an 'Officers Model' size (again, Colt nomenclature), made by various manufacturers, that is even smaller...probably what your friend is offering.
When buying a compact sized 1911 clone, be aware that the reduced length of the slide is a departure from the original design, and is less reliable, generally speaking. The shorter springs have to be just right or they can have feed problems. I'm not saying that they don't work...just that their design is less forgiving than the full sized models.
Of the off-the-shelf 1911's, Springfield, Colt, and Kimber are probably the most popular, although there are many other good ones.