Whether for a guitar amp or a Hi-Fi system, speakers are designed to reproduce sound and performances. Stereo speakers attempt to reproduce multiple sounds accurately, but guitar amp speakers compress sound, but also allow for bursts of sounds such as a pick striking a string.
Mechanical differences between the two types of speakers begin at their core. Coils and assorted wiring in guitar amp speakers is shorter, lending itself to its purpose--compressing sound. Stereo speakers employ different features such as crossovers and dampers to maximize frequency response.
While preferences may be in the ear of the beholder, the difference between Hi-Fi speaker and amp speaker cabinet construction has the ability to alter frequency response as well as tone. Guitar amps, which use closed and open backed cabinets, are rarely padded for acoustic value, as are home audio speakers. Horns, tweeters and crossovers are non-existent in guitar amps as well.