The difference between the Articles of Confederation and Constitution is that the Articles of Confederation are the rules that were agreed by the United States of America in the 18th century whereas the constitution is the rules that democratic countries and other legalized institutions develop to implement law and order in their body.
A stock market bubble is a period of growth in stock prices followed by a fall. They often form when traders enter a self-sustaining cycle of growth. They gain momentum as more and more participants enter the market.