The difference between an impossible and a 3 shove are if it wraps. The difference between a good impossible and an okay/bad impossible is how good the wrap is. If it wraps, even a little bit on their toes, it's an impossible it's just a pretty shitty one. It's like a Greco kickflip vs a Reynolds kickflip. They're both kickflips but one sucks (in fairness to Jim mine looked like his for a long, long, long time).