Analysis of the potential- and kinetic-energy changes between conjugative and nonconjugative structures led to the conclusion that there were two different types of conjugations: The conjugative stability in vinylamine and aniline is produced by an excess decrease in the kinetic energy over the increase in the potential energy (kinetic-energy origin), while the conjugation of nitroethene or nitrobenzene causes an overwhelming decrease in the potential energy (potential-energy origin). The similar analysis was applied to understanding the intrinsic difference between topological aromaticity and so-called quasi-aromaticity. Topological aromatcs like benzene and naphthalene increase the kinetic energy by interrupting their conjugations more than the reference structures while quasi-aromatics as seen in polymethine-like molecules increase the potential energy by doing so. This indicates that extra stabilization in benzene or naphthalene is produced by lowering the kinetic energy of elections In marked contrast with this that in polymethine-like molecules is due to lowering the potential energy.