Hi,
The difference is only with the registering SPN an setting the trusted for delegation setting in Active Directory
Network Service:
• Trust For delegation must be set on Computer account
• setspn –a HTTP/crm
• setspn –a HTTP/crm.server.com
Using Account
• Trust For delegation must be set also on User account
• setspn –a HTTP/crm Domain\User
• setspn –a HTTP/crm.server.com Domain\User
The CRM Fetch Reports require that you set correctly the SPN records.