I don’t want to waste too much of your time.
Spikeball is the real deal, you’re just going to pay for it. The balls are better, the net is much sturdier, which will last much longer. It will cost you mid $50’s for the set and 1 ball and close to $60 for the set and 3 balls.
Spyderball is better for kids, it is much cheaper, about half the price around $25. So without giving you each difference, buy the Spikeball set if you’re looking to play with adults and the Spyderball set for kids. Obviously, kids can play on the Spikeball set as well, so if price isn’t a consideration, go with that!
If you are an adult looking for options, check out Spikeball vs Slammo.