It's kinda both. You can sort each instructors lessons by style, difficulty and focus by using the pull down menus. Each instructor also composes their own tutorials that combine a number of similar lessons into a structure you can follow. You can also use the search feature on the main page to find just about anything you want. There's also a beginners guide: http://www.guitartricks.com/guide.php
...that takes you through several levels of difficulty to get you started.

Basically I'd just advise you to jump in and start looking around. There's probably enough lessons on the site to keep you busy for the next 20 years or so, but if you want something specific, request it in the Full Access forum area and eventually one of the instructors will get around to it.