There is no significant difference in the sysprepping and imaging of Ultimate and Enterprise.
Microsoft have chosen for some reason to produce several different versions of Windows 7 - basically choosing to service home/end users and business users with different feature lists.
No doubt there is a feature grid buried somewhere on the Microsoft site - perhaps in the marketing area of the Partner Website. Features such as Bitlocker encryption, for example, are not present in the "Retail" version but do appear in the business releases and top end versions.
No doubt Microsoft are reluctant to disclose information which could lead to a loss in revenue, but don't let that stop you doing a bit of research on Google.