We were trying to talk about different appearances for Hardie board, because you can get it to look like shakes or like, well, clapboard. I think of "clapboard" as what you call the siding that looks like clapboard. Like we have aluminum siding but it's still clapboard style.
I gave up on renovating a house after I became too disabled to finish it myself AND had multiple contractors repeatedly not understand what I was asking for, though I thought they were common tasks, so I can only offer commiseration at meeting unexpected befuddlement in that quarter.
FWIW I think we use the terms similarly. the rehab house had nice clapboard style steel siding and my current one has more of a shakes aesthetic but from wide durable, dare I say hardy, boards that are hopefully not made of asbestos.