What is the difference between the Roman Republic and the Roman Empire?

The
Romans built their republic after expelling the Etruscan king Tarquin the Proud. From that day
onward, the Romans were intensely suspicious of any kind of political arrangement that smacked
of monarchy. In the Roman Republic, power was nominally shared between two elected consuls and a
wholly appointed Senate. In reality, power remained largely in the hands of the Roman nobility;
although, they didn't always get their own way and conflict between them and the ordinary Roman
people, or plebs, was common. Antagonism was also rife between various leading personalities in
the upper echelons of Roman society, leading to frequent military conflict and outbreaks of
violent civil disorder.

When Julius Caesar became dictator, it seemed to
many that he was turning himself into a new king. To him and his supporters, however, he was
bringing much-needed stability to a system that seemed on the verge of collapse. Nevertheless,
and irrespective of the dire state of the...