Their scope is the same [0], both in terms of stated intent as well as what kind of things they could be used to attest. The only significant differences are that one is already deployed in prod while one isn't, one got a marketing blitz while the other didn't, and that they're done by different companies.

There are no vast technical differences, only incredibly subtle ones.

[0] https://www.snellman.net/blog/archive/2023-07-25-web-integri...