Nothing
Would have to see the two boats examples side by side.
But most of the time the Oceanis model name is dropped so owners say
B31, B34, B37, B40, B43, B45, etc, etc
First Owners usually say - First 40, etc to differentiate their boat from
the Oceanis line.
Cyclades line was produced for several years (2005-2007) primarily for Moorings charter company and sometimes they get confused with Oceanis line
until you see the hull or interior.
Hope that helps a little