[pm215]

From a user perspective the difference is important, because it's often the difference between "can use this for real work without worrying about exactly what's going on under the hood" and "you probably shouldn't use this unless you know you need to use it and that you can live with the performance aspects". (e.g.: booting a Windows guest under virtualization is a very popular thing to do; booting a Windows guest under emulation is probably going to be a lot of work and not actually achieve the end-goal you were after when you do eventually get it running.) They are also vastly different from a technical perspective.