The top pic is a sushi buffet. You go up and pick each peice and take it back to your seat. The pros are you select as much as you want of what you want. You can have just one peice of each or many if you choose. There is usually a large selection thus letting you get a good variety of dishes. The cons are the same. The large selection can lead to the sushi not being at peak freshness. In addition many people are passing and handling the food while getting what they want.
The bottom pic is from an all you can eat place. Each dish is made to order and is fresh. You get a menu and choose. When it comes to rolls you get a whole one. For each peice you can order by the peice so no waste. Each order is brought to you directly from the cook. The only con is the chance to over order. You need to pace yourself.
Happy eating.