I have not compared the side by side but have seen both and they look the same. They are discontinued so they don't show up on the parts catalog to compare numbers, not that that means anything anyway.
Just a tip on parts numbers... Like Dave said, most vendors have deleted the part number of discontinued parts, but Service Honda has not... If it is discontinued, it still shows on the parts list with number but with a "discontinued" price..
I tried to find the fiche it was on, but didn't want to spend the time and gave up.. but if you want to try..go HERE (Service Honda)
The part number for the 84A is different than the 83A.
However the 85LTD, 86SEI and 87A all use the same sensor part number as the 83A.
I don't know if there is an actual difference or if it's just a Honda part number lottery.