Do you know what the perfect susanoo is? Madara calls it the PS or finial susanoo because it was the furthest he got in his life time (he's susanoo's power) which he then said was comparable to bijjus. That is why he calls it perfect susanoo, because no one has ever reached that power of susanoo; it was Madara's furthest he got with susanoo, then he had to go and hide. Apart from that Sasuke did not get "PS" but he does have "finial susanoo" which means that is the final form of the susanoo, in other words he can not make it look like something else anymore, that's the furthest his susanoo will look like (all armored). PS is the power of susanoo, and sasuke's susanoo is not as powerfull as Madara's susanoo. So Madara's "PS"> sasuke's susanoo in final form, but sasuke ha a long time till he can get his susanoo to be as powerfull as madara.
In all, PS is the furthest stage of susanoo a uchia gets in there life time; that means for example, once sasuke becomes old and what not his PS> Madara's PS. Or ATM Itachi's PS <Madara's. If you watch the previous episode(like last last weeks) then you will see that sasuke has the same susanoo as the one in the new chapter.
