There are a number of differences between a library authority file and the ISNI database.
Different goals
As stated on the PCC ISNI Pilot home page, ISNI is not an authority file. Its sole gole goal is the creation of unique identifiers for public identities (the name names by which a person/corporate body is persons and corporate bodies are publicly known) that are involved anywhere in the life cycle of intellectual and artistic content. (See ISNI FAQ) Therefore, many of the use cases that govern our library authority records (e.g. establishing consistent access points for use in bibliographic descriptions) do not apply.
Is there a preferred form of name?
As opposed to traditional library authority work, ISNI does not require participants to follow any content a single standard. The group of contributors is very diverse and includes many non-library sources. Creating an ISNI is solely focused on identification. Names do not need to be unique and are not based on usage. However, it is recommended to use a full form of the name (e.g., forename instead of just an initial). A new ISNI record will be matched by an algorithm against the existing database to avoid duplicates, and a fuller form of name is helpful in this process.
All variants of a name that identifies identify a publicidentity are recorded in the same record. While within the system the ISNI creator contributor codes one name as a 700 and all others as 400, no “preferred” name is indicated in the public view.
How much information should be included?
The goal of an ISNI is NOT to "catalog" the person as can be done in current MARC authorities using the MARC 3xx 3XX elements, but to uniquely identify a publicidentity. ISNI therefore only contains the minimal amount of information needed to accomplish this task (such as as a source, dates, and external links) where necessary -- – particularly for common names.
No earlier/later names for corporate bodies!
ISNI does not recognize the concept of earlier/later names for corporate bodies. Different names for linear name changes are all considered variants. A new ISNI is only created when a change to the structure of the organization occuredoccurred, such as a merger or spilt -- split – essentially causing it to become a different organization.
Can there be only one ISNI for each person?
ISNIs describe public identities, but pseudonyms are considered separate public identities. In this case, separate ISNIs are established for each just as is being done in the LC/PCC Name Authority File.