By one definition, a snack bar may be considered a ‘restaurant’. By another, seating must be provided.
Personally, I think of a ‘restaurant’ as a place where patrons sit at a table, order food that is brought to them, and pay after eating it. There will be waitstaff to provide service during the meal.
But then, fast food places call themselves restaurants. For example, McDonald’s Restaurants. It fits the M-W definition, and what’s the alternative? ‘Fast food place’? What else are you going to call it? I think of a cafeteria as being a place where a patron serves himself. But then, I also think of a cafeteria as a place where a server dishes up the food. Are fast food places cafeterias, then? If so, why don’t people refer to them as such?
What about diners, cafés, coffee shops, bistros? Originally, a diner was a prefabricated restaurant. Today, it seems they are more likely to be in non-prefabricated buildings; i.e., a ‘stick-built’ structure. To me, ‘café’ implies a small restaurant with a limited menu. A ‘bistro’ implies a café with a more limited menu. When I was a small child, a place like Denny’s might have been referred to as a ‘coffee shop’. (‘Coffee house’ is a term that I didn’t hear come into use in the U.S. until the '80s, and meant a place where coffee is the primary attraction. Food would be primarily baked goods.) To me, a bistro seems the same thing as a café; only they’re more likely to serve spirits.
In the mid-'70s through the mid-'80s, and occasionally in the '90s, Crazy Otto’s was a favourite place for my dad and I to have breakfast. Originally, it had only counter seating and one booth. (The original location was closed after the Northridge earthquake necessitated expansion of the railroad tracks to which it was adjacent; but by that time it had two kitchens and two dining rooms. They now have four locations.) Crazy Otto’s was and is definitely a ‘diner’. To me, Denny’s is also a diner. But since patrons are seated, order their food from waitstaff, and pay on the way out, it’s a ‘restaurant’.
Where do you draw the line between a ‘restaurant’ and a ‘diner’? Or any of the other subtypes of restaurants?