There is no difference.
Although the theory is that the Ruby Red (Rubescens or Rubin) was supposedly line bred from the Maleri Island race of Aulonocara sp. ''Stuartgranti Maleri" and the German Red was supposedly line-bred from the Chipoka race of Aulonocara sp. ''Stuartgranti Maleri", the theory has never actually been proven.
With the amount of confusion between the two variants, and the fact that the line bred specimens have no real distinguishable difference (amount of blue in the face or otherwise) it's best to consider them a breed of peacock and call them pretty much whatever you want. I simply choose the term "Red Peacock" since, as it's a specimen that doesn't occur naturally, it has no scientific name, so any trade name is suitable.