Catalogue mode and shop mode

[Loopkin]

Hello everyone,
Is there a possibility to have my prestashop website on catalogue mode for every visitor, and to turn it on shop mode for a registered group of users ?
Or should I make a PHP loop to set a different ccs file displaying or not the prices, cart, etc. whether the visitor is registered or not ?

Or is there still another way to do it ?

Thanks a lot for your help