If you are going to be setting up a cold buffet or serving line inside a restaurant, a refrigerated food bar is likely the best fit for your operation. These units require electricity, but many models are on wheels and can simply be plugged into a convenient power source. These units use refrigerant and a cold-wall design to keep food in pans cool. If you decide to go with a refrigerated food bar, pay attention to where the compressor is located on the unit you select. That area of the table will require good air circulation to keep the compressor working as it should.
If you will be using your cold food bar outdoors or inside in a place where an electric connection is inconvenient, you might consider opting for an ice-cooled unit instead. These models have a well designed to hold ice, and you can place food pans on the ice or nestle packaged products like drinks down in it. These units will have a drain in the bottom for easy cleanup. While this option does require you to keep an eye on the ice levels in the table, it allows you to be a bit more mobile with your cold food bar.