Freightliner is a chassis manufacturer although Newmar uses a lot of Sparton chassis as well. The "motor" is most likely a Cummins as they are about the only engine manufacturer left in the big, over the road diesel engine market.
A comment to the OP. You should be comparing a Tiffin Allegro Bus to the Dutch Star. Phaetons, while quite nice, are positioned just below the Bus. The Dutch Star is a very nice coach and Newmar is an excellent builder. Just make sure when you look at the Dutch Star that all of the service records are there. You might want to consider hiring someone to inspect the rig before you think about a purchase.