https://www.diffen.com/difference/Democracy_vs_Republic
The key difference between a democracy and a republic lies in the limits placed on government by the law, which has implications for minority rights. Both forms of government tend to use a representational system — i.e., citizens vote to elect politicians to represent their interests and form the government. In a republic, a constitution or charter of rights protects certain inalienable rights that cannot be taken away by the government, even if it has been elected by a majority of voters. In a “pure democracy,” the majority is not restrained in this way and can impose its will on the minority.
Most modern nations—including the United States—are democratic republics with a constitution, which can be amended by a popularly elected government.