The Constitution set up a much more powerful central government to solve the main shortcoming of the Articles of Confederation.
The main shortcoming of the Articles was that they created a federal government that had very little power. It could not tax. It had no chief executive. It essentially relied on the states for everything.
To solve this, the Constitution set up a stronger central government. The states had little power over this government. The central government had a president with relatively strong powers. Laws it made were to have supremacy over those made by states. The states could not regulate interstate commerce nor could they conduct their own foreign policies. All of these sorts of provisions made the federal government stronger, thus solving the major shortcoming of the Articles of Confederation.