The Viewliner II diners have a conventional diner setup with a full kitchen at one end of the car and a dining room at the other end, seating 46.
The "Diner-lites" are 25 Amfleet II cars in the 28000 series, that were converted from Amfleet II lounge cars, beginning in 2006 and 2007. They have table seating for 49. I derived this information from the web site "On Track On Line", a very good source of Amtrak roster information.
The Diner-lites have a food prep area and counter in the center of the car, similar in appearance to any Amfleet snack bar. The differance is the additional capability (via convection oven, I believe) to re-heat pre-made meals. This allows Amtrak to provide dinner-type items on an expanded menu as well as the usual snack-bar fare. No real "cooking", however, is possible. Regular dining car tables occupy the rest of the space on both ends of the cars.
My experience with this type of equipment was on the Cardinal. One end of the car was for table-waited dining with one server (and even table cloths, as I remember). The center food-prep/snack counter area was staffed by one. The other end of the car had tables ("lounge area") for pasengers, who bought the usual snack items at the counter. You can see that the "cook" could be very busy at times. After not too long of a wait, I ended up sitting in the "lounge" with a Pepsi, chips and my Amburger. I've always enjoy their burgers (and hot dogs), but maybe I'm just not very critical. I can't comment about the quality of the dinner items, but I do know that informed opinions vary (sometimes greatly).
On the Lake Shore they may use both ends of the car for full dining because of the higher patronage of that train and, hopefully, have more staff.