In the Glade, the boys rely on one thing, order, in order to maintain their way of life. Order is what gives the boy hope. the regularity of their society, before Thomas arrives, gives them hope, the order brings happiness, and peace. Without order, the boys would realize the hopelessness of their situation, and give up, leading to chaos, and death. The boys would begin to turn on one another, and maybe even begin killing each other. The Glade is also a sharp contrast of order vs chaos with the maze around it.
The maze has no order to it, it changes every night. It is the essence of chaos , never the same, always changing, no order. This aspect is contrasted sharply with the Glade, as the ever changing chaotic maze is a perfect contrast to the orderly society of the boys. The Grievers that inhabit the maze also contrast the Glade. The Grievers have no moral code, no ethics, they are viscous beasts of chaos. Rules don't apply to the Grievers, they do as they please and therefor are extremely dangerous to the Gladers. In the maze there is no mercy, no rules, and so the boys are scared of the maze. The maze is chaotic and foreign. Its something that the boys know not to mess with, something they know to fear.
The symbol of chaos
Therefore the maze and all things in it, are a sharp and clear contrast to the glade that they boys inhabit. All of this changes when Thomas arrives. Once Thomas enters the Glade the sense of Order begins to deteriorate little, by little. The chaos that ensues in the glade makes it no different then the maze. As chaos begins to infect everything the boys have no choice but to literally dive into the center of all the chaos.