I have heard a saying, “If you have seen one Nordhavn, you have seen one Nordhavn”. They are, as you might imagine, very different due to change orders during the build and generations of “improvements”.
The 47 has the full, traditional deck on the starboard side. The 43 has a different, smaller, design side deck. The 47 is roughly 20,000 pounds more boat. This is a substantial size difference. I have seen prices all over the range...but the location, condition, age, and equipment levels have also been very different.
You should try to get on a few and get a feel for what makes you happy. There are gatherings of the boats from time to time. Perhaps that would be an occasion for you to see many in-person.