The police never but historically the military is less predictable. Militaries have their own cultures & norms, separate ideas of and sources of prestige & reward, commitment to the military as a valuable institution in its own right etc. Officers are also educated and high ranking ones are powerful political actors within their own domain in way almost no police are. This can really change their relationship and susceptibility to power and political influence.

These aren't universally positive attributes I'm not necessarily praising them. But militaries have come down into a very broad spectrum of positions around specific coups, revolutions, insurrections etc including abetting or openly joining them, both pro- and anti-democratic.

This is also why the second trump term has been so focused on officer purges! You definitely want the military to come down on your side and making sure all of its leadership is on your side is a reliable step if you can take it.

Americans should absolutely imo not be looking for their military to help them with the problems they're facing. But depending on the exact arrangement, people in other countries may have good reason to hope for that.