Shinsen-gumi may be described as "a group of pro-shogunate killers" (actually their purpose was to capture, but there were too many lawless roshis who tried to escape, or who tried to attack them with their swords), and they were engaged through the Ikedaya Incident, etc., in controlling Sonno-joi extremists and lawless roshi's hiding in Kyoto.
新撰組はいわば“佐幕派の人斬り集団”（本当は捕縛することが目的なのだが、逃げようとしたり、斬りかかって来る不逞浪士があまりにも多かったため）であり、池田屋事件などで京都に潜伏する過激派尊皇攘夷論者や不逞浪士の取り締まりにあたった。