Adu is the god of prophecy and riddles. Some believe she is a direct descendent of Kronorus, although there is little to no evidence to support this.
This is information that anyone who has gone out of their way to learn would very easily find. Someone with Knowledge (relgiion) as a skill would automatically know this information. Someone who is a follower of a deity would know the General Knowledge for that deity.
This represents information about a deity that is less well known, but not intentionally hidden. With a little research you should be able to find this information. A Knowledge (religion) roll of 15 should suffice to divine information from the Advanced Knowledge section. A follower of the deity would only need to roll a 10. A more devout follower may know this information automatically.
Obscure Knowledge represents what only the most devout followers of a religion would know about. For somoene outside of the relgion to find this information, it would take significant research. A knowledge (religion) roll of 25 would be required. Followers of the religion would have this reduced to 20.
Hidden knowledge is information that has been intentionally obfuscated or even had references to it destroyed. Usually this will feature facets of a deity that would be considered evil or repulsive to the deity's followers. This information can only be uncovered through gameplay.