@tomr,
Well, that does look like an irreducible metaphysical difference...
Holism is not the only alternative to reductionism. Any serious look at relations between elements in a system will lead you to understand that properties emerge from the system, not from their components.
You can clap hands with two hands, not with one hand. There's nothing inherently 'clappy' in a hand.
That's what you did not understand in the clock example: the structure, the blue-print of how the clock is designed, is what determined the shape of each cog in it, so the determinism here works
from large to small. And ultimately, the structure is what makes the clock work, not element A or element B but the whole design and interactions between those elements.