Both the Articles of Confederation and the Constitution explicitly prohibited the states from exercising certain powers, but the Constitution restricted the powers of the states far more than the Articles of Confederation had done. Interestingly, the section in the Articles relating to the prohibitions on state powers is in fact far longer than the corresponding section in the Constitution. Most of this difference in length, however, can be accounted for because the Articles had tried on many occasions to list numerous qualifications or exceptions to the named prohibitions; the Constitution, on the other hand, simply prohibited the powers outright or with very terse exceptions. The Framers kept all of the important prohibitions on state powers that had existed under the Articles, and then they added a few more.
In both the Articles of Confederation and in the Constitution, the most common reason for denying particular powers to the states was to keep the states from passing laws that would interfere or conflict with the powers that had been granted to the federal government. Hence both compacts either prevented or restricted the states from entering into treaties with foreign countries or with each other, granting letters of marque and reprisal, keeping warships and troops in times of peace, or starting wars. And whereas the Articles had prohibited the states from laying any duties that might interfere with international treaties, the Constitution prohibited them from laying almost any kind of import taxes whatsoever. The reason for the more comprehensive restriction lay in Congress’ new power to levy its own import taxes: after the Constitution was ratified, it would become important to keep the states from interfering with the new taxing authority of the federal government. The only other prohibition that each document shared was the one forbidding states from granting titles of nobility (and in each case the federal government was laid under the same prohibition).
In addition to repeating many of the same prohibitions that the Articles had named, the Constitution added a few more. The Framers decided that coining money should be the exclusive power of Congress, stipulating that states would henceforth be prohibited from doing so. They also chose to prohibit the states from laying taxes on exports as well as imports, principally to keep the seaboard states from laying heavy burdens on the inland states as goods passed through their territory. Most of the new prohibitions, however, were designed to prevent the states from passing any more laws that many delegates considered unjust. Consequently, the states were also prohibited from printing paper money or passing any bills of attainder, ex post facto laws, or laws impairing the obligation of contracts.