Imperial Dalek
The Imperial Daleks were a faction of Daleks loyal to their creator, Davros, rather than the Dalek Supreme. The Imperial Daleks had white livery with gold bumps, and high-pitched voices. These Daleks were not descended from the original Kaled mutants, being instead made from the modified heads of human corpses infused with the Dalek factor. They were destroyed along with Davros' laboratory in the Tranquil Repose funeral home on Necros by the original Daleks. There was an Imperial Glass Dalek - it was prototype Dalek with a transparent casing that revealed the mutated head inside. (DW: Revelation of the Daleks
Later on, Davros had somehow escaped whatever fate the Daleks had in store for him and had gained control of Skaro, becoming the Emperor. He recreated the Imperial Daleks by grafting bionic appendages onto the bodies of Kaled mutants. Their casings now had golden eye-stalks and a lozenge shape on the front of their casings, and their gold plungers were slotted to fit into machinery.
A civil war, ostensibly over racial purity, broke out between the original, now Renegade Daleks, and the Imperial Daleks. Although their firepower was weak, Imperial Daleks augmented their battle tactics with the Special Weapons Dalek. It is not clear if any Imperial Daleks survived, as both Skaro and the main Imperial Dalek warfleet were apparently destroyed by the Hand of Omega. (DW: Remembrance of the Daleks)
In the Big Finish Productions audio play Terror Firma, Davros survived the destruction of Skaro and created a new army of Imperial Daleks from Earth's population by releasing a virus that turned humans into Dalek mutants. Davros' mind was taken over by a completely Dalek personality, and this new Emperor assumed control of the Imperial Dalek army. It was not stated if the Imperial or Renegade factions were dominant at this point or after.
Special Weapons Dalek
The Special Weapons Dalek is a heavily-armoured Imperial Dalek first seen in Remembrance of the Daleks. Unlike a conventional Dalek, the Special Weapons Dalek has no manipulator arm or eye-stalk. Instead, it has an enormous energy cannon mounted on the front of the armoured casing in place of the usual small gunstalk and several red squares around the dome in place of the usual eyestalk. Special Weapons Daleks do not appear to be able to speak, but do have massive firepower, said in the BBC Dalek Survival Guide to be up to 50 times more powerful than a blast from a regular Dalek gun.
In Remembrance of the Daleks the Special Weapons Dalek's firepower was so great that one shot completely vaporised two conventional Renegade Daleks, leaving only a pair of burn marks, and the armour was sufficient to deflect conventional Dalek energy weapons without suffering any apparent damage. Like the other Imperial Daleks, its livery was white with gold bumps, but with sections of metallic grey armour covering most of the upper portion with much battle scoring. The Special Weapons Dalek was also mentioned in the novel War of the Daleks, and the Big Finish audio The Genocide Machine.
In Ben Aaronovitch's novelisation of Remembrance of the Daleks it was stated that the enormous power source required for its weapon resulted in high levels of radiation being released and altering the structure of the Dalek's brain, resulting in insanity. It was only used in extreme situations and was unofficially known among the Daleks as the "Abomination."
Special Weapons Daleks would have been featured in the aborted 30th anniversary film The Dark Dimension. According to the BBC Dalek Survival Guide, Special Weapons Daleks also come in both Marine and Airborne forms.