As an expert in image processing:

.png supports pretty extreme compression, while a jpeg can also be lossless. The extensions tell you nothing except which family of algorithms was used to encode/compress/store them.

Webp though, webp is only used for the internet. I mean, you could use it other places, I guess.

Congrats! Mine also came yesterday. I grabbed the 2 TB with Steam controller. I think you and I were in the same batch of emails!