Table group,Type,System,shared table in Ax 2012

->> Table group. The TableGroup property of a table can be used to choose tables to include in definition groups for export.   It can also be used to determining  which types of tables should be held in the record cache.

->> Table type. The  TableType property of a table determines where the table is stored. The options are:
   --->> Regular: stored in the Microsoft Dynamics AX database.
   --->> TempDB: stored in the TempDB database.  When you restart an Application Object Server instance or database, all  tables in the TempDB database are dropped and recreated.
  -- ->> InMemory: held in memory only during the current Microsoft Dynamics AX session.

->> System table. A table that is used by the Microsoft Dynamics AX system, not for customer data.

->> Visible. A table that is visible in the AOT.

->> Shared (SaveDataPerCompany = No). Shared tables are used by multiple companies. Tables that are not shared pertain   to a single company.