Wes identifies the gun carried by the home invasion crew as an MP5, and describes it as an assault rifle. The MP5 would correctly be classified as a submachine gun, a fully automatic rifle that fires pistol rounds. By contrast, an assault rifle fires higher powered rounds at the expense of heavier weight and generally larger size.
The brother who was murdered had dyscalculia, dyslexia's lesser known cousin. It is very similar to dyslexia in many ways, but it has to do with numbers, where dyslexia is with words. And though they are similar, they are still different learning disabilities.