Royal Guard were Emperor Palpatine's personal guards who served to protect him and would accompany him on many occasions. Since he doesn't make any exclusive use of them, they would occasionaly be served under Darth Vader .
Senate Guards and Senate Commandos were the elite security force of the Galactic Republic that was tasked with protecting politicians and the Galactic Senate, including Palpatine, during the Republic era. The elite Senate Guards were chosen to become part of a division called "Senate Commandos" to carry out vital missions for the Republic and protect the Supreme Chancellor of the Republic.
Serving the Emperor
The Royal Guards were trained to be elite, silent and deadly with abilities unrivaled by any other. They would carry force pikes and accompanied Emperor Palpatine frequently during the time of Galactic Empire. It wasn't rare to see Darth Vader protected by the Royal Guard as he was the Emperor's right hand man and would often be seen escorting the Sith Lord.
The Liberation of Lothal
The Royal Guards appeared by orders of the Emperor to destroy Ezra Bridger for demolishing the remains of the Jedi Temple that Palpatine salvaged. The guards were in a battle suit instead of robes, and used their Force Pikes on Ezra. Ezra then throws a rock and dispatches all of the guards and some Stormtroopers that assisted them.
- "Empire Day" (First appearance) (Appears on viewscreen)
- The Royal Guards that appeared in Family Reunion and Farewell wore a battle suit instead of robes, possibly due to the expensive cost and time-consuming process of producing robes in CG animation. Furthermore, their helmets are designed differently. These two factors cause them to resemble their successors, the Elite Praetorian Guards of the First Order seen in The Last Jedi.