a dining area because you can expend it whereas a nook can sit only as many seats as there is space,

A "Nook" is a dining area. Or you can cal it a breakfast bay. It got the name with the use of what is almost always a cute but useless space sucking clipped corner bay window.

You are showing two different "open" floor plans. A kitchen, a dining area, a dining ROOM ? All will hold a table and chairs . Any and all are only as good as the total home plan, and the main living floor of that plan.

If you are asking which of the to plans above are better? Nobody can answer without seeing rhe entire first floor, and knowing more about your needs. A nook is a dining room/area by another name.........and both above are OPEN to the kitchen.

I voted for a kitchen nook because I live alone, and I really use it for other projects (i.e. I don't eat there unless I have guests). However, your floor plans don't show a kitchen eating nook.....that's almost 150 sq ft! It's really a dining room.....Maybe it's a casual dining room, but it's not a "nook". Kitchen eating "nooks" are usually more like 50 sq ft (can fit a small table for 3 or 4 people), and don't communicate with any room other than the kitchen.