You're right, or actually close. 2mm difference. Heritage BB is 41mm, new bronze BB is 43mm. The Heritage BB wears much bigger than 41mm due to the case shape IMO.
https://www.tudorwatch.com/watches/heritage-black-bay/m79230r-0001
https://www.tudorwatch.com/magazine/article/baselworld-2016-black-bay-bronze
And the gen Bronze BB is a new proprietary aluminum allow bronze that Tudor/Rolex developed that is supposed to patina much, much slower and even than other common bronze allows like CuSn8 found in other bronze models. The rep won't have this characteristic as I'm sure the allow used is whatever the cheapest one they factory could find.