[Ultra Sonic 007]

The North American size discrepancy is simply due to proximity:

A treatment on how the Blue Marble pictures were taken is provided here.

[rx]

Yeah, I’ll give you that one. I’m not perfect.

[sargon]

Actually, in that composite image, the size of the circular projection of the sphere is almost the same for each sub-image. So it's not really from a greater distance each time, or the "circle" would be smaller in each picture.

What you'll notice after some observation is that the ANGLE is different in each sub-image.

So effectively the image of North America is progressively smaller because of being taken at a different angle each time, further away from North America (but NOT significantly further away from the globe itself).