Some important differences between these 2 references, although they both share a blue dial.
The Differences are about the bezel, and the dial:
Mare Pre V: A flat bezel, and a different layout of the dial, with indexes which are more located at the center of the dial
Pam 6:
The bezel is a bit curved at its outside part, and the indexes are close to the bezel:
You will also notice that the hands ( minute and hour ) are not blue painted on the Pam 6.
Hope this help.
Nicolas