The rear down tubes that the rear seat belt bolts to are different.
Honda changed the mounting of the seat belt pivots in 2017 I think.
The shoulder bars are part of the lower seat frame so that shouldn't matter. But I do believe Honda changed the way the nets mount when they added the shoulder bars and the center portion of the cage is part of that.
For reference Honda part numbers are broken down as such:
The first 5 identify the type of part (body, fuel, oil filter, spark plugs, wheels, etc) so it won't change between model years.
The 2nd set of 3 numbers is the model reference for which that part was first used. So any new part that was produced for a particular model will have that models code. If that part is later used in a different model then the entire part number wont change and will reflect the original model use.
HL1- Big Red
HL3- Pioneer 700
HL4- Pioneer 1000
HL5- Pioneer 500
HL6- Talon
HL7- Talon 4 seater
This applies to every honda product made, if you ever see a part number with a 3 digit number in the middle and no letters its a really old number since they used numbers back then.
The last 3 digits will reference a updated/superseded part or color code.
A00- Original part created
A01- Updated or superseded for whatever reason
A00ZB- Painted or colored part for which there are other options for that model. Pioneer/Talon body panels, etc.