Hi! On the WebP version of the game are scenes with loss of quality, but compression allows you to optimize space on your device. The high-res uses the png picture format, which allows you to see all the interesting moments in the original resolution! It's hard to say exactly what the difference is, but it's important to note that the first is compression (inevitable loss of quality, and the second is lossless original resolution), as in audio formats.
Glad to have answered the question and have fun playing SlutCraft!