The User Sessions API enables you to obtain data about user sessions. The API uses User Sessions Query Language (USQL) to query the required data. Both calls return the same data, differing only in how it's represented.
The GET table request executes a USQL query and returns results as a table structure of the requested columns.
The GET tree request executes a USQL query and returns results as a tree structure of the requested columns—a flat list containing the requested columns.
User session structure
Learn the structure of a user session that contains all possible fields.