I am no expert on those, but I have had an interest in the Hans Christian boats since I first saw them in the 80s. I like traditional styled boats and I like a "salty" looking boat too. So, take my comments below with a splash of salt water
Quick and Simple answer: The Christina design is a more 'modern' looking boat (contemporary production looking boat for 1980s) rather than the "traditional" (salty, similar to a Colin Archer) styled boat that made the HC name so famous.
My take on it is that the HC builders made their name with the traditional boats (which were also appealing to the many (the boat buying
market in the USA) who saw the Westsail 32 and 43 boats from the mid 1970s) and they needed another boat to offer the market for those buyers who did not like the "old style" detailing on the decks and hull
of the traditional styled boats.
Another opinion: When I see a Traditional Styled HC 43 looking Bristol or "salty and weathered" at a dock
or anchorage, I think "VERY nice!" Because it has a distinctive design/look and styling that seems "salty and ready to go across oceans." That distinctive styling looks "sweet" and it just seems "timeless." I like it, and find it very appealing.
But, if I am told there is a HC Christina among other boats in a marina, I ask "Which one is it?" (Because looks like many other boats.)
Hope that helps.