In the modern world order, different forms of governance hold sway in several nations globally. An impartial journey into the dynamics of political power must necessarily examine two primary systems – democracies and autocracies. Both systems, situated at contrasting poles of the governance spectrum, offer useful lessons on political power’s structures and mechanisms.

By design, democracies revolve around the principle of ‘power to the people,’ where the citizenry stands at the helm of selecting public representatives. On the other hand, autocracies operate under the principle of concentration of power in the hands of a single entity or individual. These fundamental attributes shape the dynamics and exercise of power in each system.

In democracies, power is often decentralized and distributed among various elected officials and regulatory institutions. Political power is dynamic, continually shifting based on the will and whims of the populace. Elections serve as significant political events, shaping the course of policies and influencing power dynamics. This mechanism inherently affords checks and balances and promotes political agility. Yet, complexities arise when polarization and partisanship turn healthy political competition into a battleground for supremacy. The dynamism of a democracy, thus, can be both a strength and a source of volatility.

On the flip side, autocracies are marked by centralization of power, where power dynamics are considerably more static. A single leader, political party, or entity exercises unrestrained control, leading to a lack of political competition and limited participation from the populace. While this centralized nature can foster political stability, it often comes at the expense of personal freedom, civil liberties, and equity. One of the fundamental challenges in autocracies is the potential for power corruption, as absolute power tends to breed absolutist tendencies.

Despite the stark differences between the two, an intriguing aspect of autocracies and democracies is their susceptibility to similar issues. Both systems grapple with corruption, nepotism, and populism. Autocracies face them due to lack of checks and balances, while in democracies, these issues occur despite the checks and balances in place. Understanding these shared challenges reveals how political power, in any form, can be misused if not held in check.

Finally, it is also crucial to discuss the dynamics of change within these systems. Democracies thrive on evolution, learning, and progress, continually adjusting to changes in societal attitudes and beliefs. However, autocracies primarily evolve when external pressures or internal unrest become too formidable for the existing power structure.

In conclusion, the dynamics of political power depend greatly upon the system in place – the egalitarian nature of democracies versus the centralization of autocracies. Democratic and autocratic regimes each possess strengths and weaknesses, and the degree of their effectiveness relies heavily on numerous internal and external factors. Most importantly, the use and misuse of power in both systems underscore the significance of continuous vigilance, transparency, and accountability in maintaining a fair and just political order.