Log Category
Includes information about database activity, including every data manipulation language (DML) statement or inline SOQL or SOSL query.
Includes information for workflow rules, flows, and processes, such as the rule name, the actions taken, and so on.
Includes information about validation rules, such as the name of the rule, whether the rule evaluated true or false, and so on.
Includes the request-response XML that the server is sending and receiving from an external Web service. This is useful when debugging issues related to using Force.comWeb services API calls.
Apex Code
Includes information about Apex code and can include information such as log messages generated by DML statements, inline SOQL or SOSL queries, the start and completion of any triggers, and the start and completion of any test method, and so on.
Apex Profiling
Includes cumulative profiling information, such as the limits for your namespace, the number of emails sent, and so on.
Includes information about Visualforce events, including serialization and deserialization of the view state or the evaluation of a formula field in a Visualforce page.
Includes information about calls to all system methods such as the System.debugmethod.