In one context you are right in that most BA Business Class is the same (747 / 777’s). However there are product variances on the LCY-JFK services along with the 767’s and A321 midhaul services. You can argue they are consistent in that they are all flat (except when a short haul 767 gets put on a longhaul flight). So it isn’t in the league of say switching an Emirates A330 business class to an A380 business class, but there are subtle (and maybe not so subtle) difference between the products. I haven’t flown them all so couldn’t go into detail. Others on here would be in a better position to go into detail on this.