There are a lot of different sizes of 24, 26, etc. I have heard of people saying 28 and 29 are the same, others say they are not. But, I think everyone agrees that 28 and 29 are smaller rim sizes than 27. (Exception, the vintage Raleigh DL1 was 28 inch but that was a big 28 inch.) Bottom line is it can be quite confusing.
It is most clear if you refer to numbers like 559mm for 26 inch, 630mm for 27, etc.
Tire Sizing Systems
But, I think 650b and 700c are unambiguous, so referring to those sizes is not confusing.
I have seen recent reference to 27.5 inch but quite frankly I have no clue what that is. I suspect that some committee of marketing managers had a conference call where they decided to give a new name to something old in the hopes of increasing $ale$ ... ... and bonu$e$.