The four levels of Sheev Palpatine, AKA Darth Sidious:
The Emperor: the vague, foreboding title used exclusively for anything post-RotS.
Examples: “The Rebellion fought to overthrow the Emperor.” “The Emperor visited the planet.”
Palpatine: the formal, overarching historical reference, but more personal.
Examples: “Palpatine ruled the galaxy”, “Palpatine was plotting against the Jedi”.
Darth Sidious: The Big Bad, the ominous Final Boss, a name that fully recognizes his evil and power.
Examples: “While Darth Maul was terrifying, even he was frightened of Darth Sidious.” “The Jedi were no match for Darth Sidious.”
Sheev: He’s just being a troll.
Examples: “Padme told Sheev about how wonderful her friend was, and so he had her friend assassinated.” “Sheev built the Imperial ballroom over the old Jedi mausoleum so he could literally dance on their graves.” “Sheev made Padme lose the will to live, blamed it on her husband, and then used her clothes to sell merchandise.”