Illustrious 0.1 was trained off a Danbooru dump made sometime in 2023 (can't find month), while Anima is trained off a dump from September 2025. In addition to knowing newer properties, this means Anima has been impacted by Danbooru renaming certain tags and as a result it will use slightly different terminology for certain things Illustrious already knew in addition to entirely new knowledge. The most prominent of these is that while Illustrious 0.1 uses the tag "anime screencap", Anima uses the tag "anime screenshot" as it postdates the April 2024 rename. Most old names are preserved as redirects (I don't know how Anima handles these), but some have been deprecated, split into multiple tags, and/or split into a combination of tags. To confirm if a tag has changed, you can put it in "tag history" under Danbooru's "More »" header, and see their wiki for usage guidelines of tags (be warned Danbooru is very much NOT a SFW site).
(Illustrious 1.0 and later also had training on a June 2024 dump. I'm not sure how it handled the renamed tags, but it's not like the newer versions are worth using)
I wound up mentioning this elsewhere and figured it was worth saying to a wider audience so I wrote a quick article. If there's any longer list of renamed tags out there, I'd love to see it.