In both anime series the MC are sent back in history in order to protect something . The only difference is that in drifters there are many other creatures like Elfs , dwarfs and others. In Katsugeki/Touken Ranbu the MC are animated swords that must protect the history and in Drifters they are warrios from different eras of Toyohisa's world who were thought to be dead.
Do you like historical/battle action shows with AWESOME sword fights?
The main difference between the shows is that the world in Token Ranbu definitely has a touch of fantasy whereas Rurouni Kenshin has a realistic setting but if you like well choreographed fights and shows set in historical japan than give these series a try.
Both have elements of the Shinsengumi, But Touken Ranbu is about historical swords transformed into men to protect history. The swords from the shinsengumi include Izuminokami Kanesada(uchigatana) and Horikawa Kunihiro(wakizashi) wielded by Hijikata Toshizou
Swords, boys, light beams, intense action choreography, Japanese history, and both are based on games... these two shows are surprisingly similar.
Sengoku Basara has a brighter palette and a more positive feel, whereas Katsugeki is much darker. Outstanding action in both shows, Katsugeki being the more polished of the two with very good utilisation of CG.
Neither are exactly shows to watch for plot or character depth, but if you're a fan of the games or are looking for some fast paced shiny action fuelled by shouting, give Basara or Katsugeki a try.
Its an alternative setting like MAL say. Katsugeki is more serious, more angsty and has a better animation in my opinion (I love hanamaru too don't kill me saniwas) but both are worth watching if you love Touken Ranbu.