The US is a Constitutional republic where government power is limited. The operative word is Constitutional!
North Korea, Syria and some of the most oppressive places on earth are technically 'republics' meaning they do not have a monarchy and that they pretend to have representation of the people.
There is nothing magic about the word republic. It is a well written and well observed constitution to limit government power and insure individual liberty that makes the difference.
I argue that the U.S. is a republic and NOT a democracy..
Although a very unique republic at that..
A Banana republic is in fact a democracy(central government)..