Democracy:
A government of the masses. Authority derived through mass meeting or any other form of "direct" expression. Results in mobocracy. Attitude toward property is communistic--negating property rights. Attitude toward law is that the will of the majority shall regulate, whether is be based upon deliberation or governed by passion, prejudice, and impulse, without restraint or regard to consequences. Results in demogogism, license, agitation, discontent, anarchy.
Republic:
Authority is derived through the election by the people of public officials best fitted to represent them. Attitude toward law is the administration of justice in accord with fixed principles and established evidence, with a strict regard to consequences. A greater number of citizens and extent of territory may be brought within its compass. Avoids the dangerous extreme of either tyranny or mobocracy. Results in statesmanship, liberty, reason, justice, contentment, and progress.
Source: U.S. Army Training Manual No. 2000-25, published by the then War Department, Washington, D.C., November 30, 1928; withdrawn five years later by Franklin D. Roosevelt!!
In this regard, let's also not forget the following quotes:
"Democracy is the road to socialism." - Karl Marx
"The goal of socialism is communism." - Vladimir Lenin