Boots or socks
Some dry suits have boots and some have socks. With most suits you buy from the shop you cannot choose if you want boots or socks. With brands that make customised dry suits, you usually do have this choice.
The advantage of boots is that they are attached to your suit, so they are easier and quicker to pull on. It is important that they fit well, so they do not slip off in the water. To prevent the boot from slipping from your foot, the new generation of boots for dry suits has the option to tighten the shaft with Velcro. The disadvantage of the boots is that shoe size is important, and it should be accurate, while feet of various sizes can fit into the same neoprene sock.
The big advantage of socks or soft boots is that these fit your foot tighter. A sock is made of neoprene and very flexible, so that it fits better, but this flexibility also means that the sole does not offer enough protection against stones and other sharp objects on the bottom. That is why you wear a rock boot over it. The advantage is that you can just buy this shoe in your own size, and that it cannot slip off. A dry suit with socks does take longer to put on, because you also have to put on the rock boot.