They are the same camera except for the Kowa name plate added.
After 1960, all Kowa cameras were named just Kowa.
Kallo name was from Greek meaning beautiful.
They were (and still are) the fastest 35mm lens-shutter cameras ever made.

The Kowa 140 is fitted with 85mm F3.5 Prominar and the Kallo 140 with
ultra fast Prominar F1.4/45mm. I also have a wide angle Prominar for
the series but currently it is missing in the chaos of my room.

*