directed means will be used at deeper depths (greater than 10m) rather than mainly freediving (generally less than 10m unless expert.
The Sea Life is a updated dedicated divers camera
itself with a built in housing in the mold
of the original Nickonos cameras from the 1960/70's - small ,light and tough. The latest versions seem to have many of the latest features demanded.
Not having used one personally I cannot speak for their relative photographic merits.
They are the only real alternative to a camera
and housing for a scuba
Whilst the olympus and Nicon aw100 have great waterproofing for so called tough cameras you would be tempting fate using one regularily for scuba photogaphy.