Comment by DaSHacka

Exactly this

archive.org is the more straight-laced archive that doesn't circumvent sites that try to block it, and removes content they deem 'problematic' even if not illegal or requested by the site owner.

Meanwhile archive.today/ph/is/etc is the guerrilla alternative run by a die-hard datahoarder that seeks to archive the information itself, bypassing whatever blockers/login pages/whathaveyou to achieve the result.

It's nice to have both options. When I archive a site, I usually use both for added resiliency.