Difference between Types,Types,Type-POOL and TYPE-POOLS in SAP ABAP

“TYPE” is an ABAP keyword which is used to reference built-in data types of ABAP. For ex: When you use “TYPE” keyword while declaring variables as below:

FIELD-SYMBOLS <name> TYPE string

TYPES is another ABAP keyword which is used to define local types.

TYPES <variable name> TYPE STANDARD TABLE OF string WITH DEFAULT KEY

In case if your group locally defined types which can be reused across many modules then you can use TYPE-POOL.