Binds: You are able to bind one weapon or peice of armour, along with runes or arrows (up to 125 of these ). The number of RS gold bindable weapons/armour increases as your level goes up. Guardian doorways: you can only open these once you've defeated all monsters in the room. Skill doorways: you will need a certain skill level to open these. Puzzle space: like it states, a puzzle. If you are stuck, search for a dungeoneering guide on the internet. They record all the puzzles. Passing: reduces your experience by a fair chunk. Seriously, do not die. Nawt kewl.
I will try to clarify it super-easily. You will find a lot of dungeons, known as floors. Consider these as mazes that you get XP for by reaching the finish. As you level the skill, you unlock additional floors. The floor number doesn't have anything to do with how tough the dungeon is. The sole difference between each floor is that the boss looks different as well as the scenery changes.
The sophistication determines how hard the floor is, and buy OSRS gold also the size determines how long it will take to complete. Both are dependent on the party boss. Everyone chooses complexity 6 since you get the most XP like that. The dimensions (the number of rooms there are), again, is dependent on what the party leader selects. When there's 5 people in your party, expect it to be set on large and take a lengthy time to finish.