Order will keep you out of trouble, be well organized, since of control, no room to be stressed out and in general can make life easier. On the downside, order can be boring and you might miss out on having fun and you could become OCD.
Chaos will cause us to live life to the fullest and take risks that we normally would not take and we can get a break from everyday living. Chaos is also destructive, It can cause damage, you'll act without thinking or taking pre-caution, you can cause messes that will be harder to clean up.
The Cat represents overwhelming chaos while the Goldfish represents overwhelming order. In the story, Cat balances a teacup, milk, a cake, three books, The fish, a rake, a toy boat and even his umbrella while he's on top of a ball which upset the Goldfish. The Fish is too paranoid and uptight to pay attention to the fun in life.
Childern are a good example of the two. They will listen to both ideas without being too consumed or overwhelmed in either.
Sources:
Studymode essays Cat In The Hat
http://www.studymode.com/essays/Dr-Seuss-The-Cat-In-The-1233946.html