Assuming they're square. Roughly calculating (23 million pixels between the two with no space between 7.5 microns,) that's 25.432mm^2. they've said they're the size of postage stamps. This ties in.
I think it's near safe to assume there's no real gap between pixels and thus indiscernible. The lag might be a thing.
Once again, the absolute size is irrelevant - postage stamp or otherwise. It's optically scaled to fit your field of view - essentially under a microscope. There are VR devices with 4k screens already, and it's still not enough to be indiscernible to the eye - especially for things like text.
