Item Category Group
This indicator is part of the link between the material master and the sales document. When you create a sales document item for this material, the combination of the item category group and the sales document type determine the item category. You can find this field on the Sales: Sales Org Data 2.
General Item category Group:
General item category grp is used in the sales processes like BOM, where we have higher item category and the default item categories.
General Item category Group is an extension item category group. Example: if one select item category group as NORM, but under item category group, NORM can further be classified as Service item, packaging item or Normal item using "general item category group".
Also, General item category group is maintained at client level, this field can be maintain from Basic Data View of Material Master. Thus in case item category group is missing, then general item category group is used for item category determination.
Item category group:
Item category group determines how a material is processed in the sales order. When processing sales and distribution documents, the system uses the item category group to determine the item category and proposes it in the respective document. Item category group is defined in the Sales Org View 2 of Material Master Record.
Example, in the standard SAP System, the item category group NORM is defined for materials kept in stock and the group DIEN for services and non-stock material.
General Item category group is not valid for the Sales organisation & Distribution channel and mainly used for "Inbound delivery" MM area (is used for other module as well).
Item category group is valid for Sales organisation & Distribution channel (SD), used in Outbound delivery.