There are many levels to this legal stuff.

The congress proposes Bills. If they all pass it and it gets signed by the President, it becomes a Law. The IRS has rule making authority to figure out how to implement stuff, so they have Code of Federal Regulations. The Government has a lot of notification requirements, so you see this as disclosures, notifications, and the IRS issues Publications, and Instructions, especially for Forms. There also are Tax Topics, which are directed more to the "man on the street" and not full of the glossary and terms used in the regulations (not full, but there still is a lot).

And that's why you see the same subject in various perspectives.

And right now, for instance, many of the things that were recently updated or introduced during the pandemic years are just starting to kick in (take effect). The IRS will "issue guidance" and sometimes, they are taken to court and lose a ruling, and have to start over with how they thought they would implement some new law.

And now, when you read articles or IRS materials, you also need to pay attention to dates. A Pub from tax year 2021 might not apply to 2024.

My father always pointed out this is Tax Practice, because no one gets it Perfect.