CRM_ORDER_READ :
1. Get all the Service Contract details.
Note: Pass the requested objects to fetch only the required details.
This can also be used to get the details of
activities/leads/opportunities etc.
2. CRM_ORDER_READ is a function module which can be used to get the
details of any business transaction based on the Header GUID, Item GUID
or both.
3. Always pass the IT_REQUESTED_OBJECTS structure to this function module to fetch the required details only.
4 . This function module can not be executed directly instead SAP has
provided a report CRM_ORDER_READ for the same for testing purpose. We
can pass Business Transaction Number (Object ID), Header GUID or Item
GUID to this report to get the required details.
CRM_ORDER_READ_OW
is used to Read the Header Details for a Business Transaction. Pass the Header guid.
CRM_ORDER_READ returns all information of a or a business transaction.
CRM_ORDERADM_H_READ_OW returns only header details for a business transaction.
I normally use CRM_ORDERADM_H_READ_OW when I want header information of
an document (like document number, description. creation date, etc...).
When I need other things like partner information, document flow
information, product information (etc...), I use CRMD_ORDER_READ.
Whenever we need to read order data from outside the order we need to
call CRM_ORDER_READ. For example, inside a campaign BADI if we want to
read the order details, we need to call CRM_ORDER_READ.
CRM_ORDERADM_H_READ_OW is an object work area FM. *OW function modules
are only called from within the order. For example, during partner
determination BADI of the Order, we want to read the Admin Header
Structure (ORDERADM_H) of the same order then we will call
CRM_ORDERADM_H_READ_OW