There are 3 main types of ladders and steps. Each with their own design function.

A-Frame Ladders are used when you do not plan on having a deck around the pool. A ladder equal on both sides, for entry and exit of the pool. These are simple, effective, and cheap for the most part, although there are some fancier ones ill discuss a little further down in entry systems. A-Frame ladders come in a few different varieties, standard ladders, some with added protection from unauthorized entry like a Roll Guard ladder, or one with removable steps. There is also a heavy duty version if you need a little stronger ladder.

Deck ladders are used exactly as named, for use with some sort of pool deck. Rather you build a small 6x6 or a full wrap around deck, this is a small inexpensive way to enter and exit the pool. They mount to the decking and are basically half of an A-Frame ladder. Because it is about half of an A-Frame ladder, they typically cost half as much as a comparable ladder.

Entry Systems can be a few different things. Most commonly, they are deck mounted or used with a deck, and only have steps inside the pool. There are several designs available, weight limits, and colors. This is mostly personal preference. There are a few that are just like A-Frame ladders but have either walk up step on the outside or inside, like a hybrid of some sort. Some even have a lockable gate on the outside.