Jiroutachi (the red winged one) is the extroverted brother who likes to drink sake and celebrate with the other Touken Kouma, whereas Taroutachi is more of an outcast and doesn’t get the whole deal with earthly things (let’s not forget he used to be a sword offered to gods) so he keeps to himself almost all the time.
Gave them their sword crests as Cutie Marks for the time being until I can think of a more proper design.