Org Model in SAP CRM

Hello Every one,

I have been seeing so many blogs and wiki's - I would like clarity with you on this Org Model in SAP CRM.

1. For Org Model in CRM - Do we have replicate ECC Org structure to SAP CRM ?

2. What is the difference between creating the Org Model manually in CRM and assigning ECC Sales Org Units under the Functions Tab of Org Unit .

Eg - Assinging Sales org 1000 , Distribution channel 10 and Division 00

Eg - Sales office 10 and Sales group 20

Your inputs are really appreciable.

Thanks in advance

Amrita