Here IAM lists all users currently being managed. In this example just 2 users are in the system. But these 2 users have a total of 9 accounts between them.
Here we see the first user listed and alot of detail stored in the master database and also data received from each of the remote IAM servers. This way we get up to date information about each account. For example, if you had a quota on a users email account, it could display current used quota and max quota.
This is the second user. They have different accounts, but they are still all listed in detail here.