I'm not sure they always have the same color/clarity. I was looking around for diamonds at one point recently (friend's looking to propose) and the synthetic selection didn't seem to go all the way up to the highest end of the scale.

Also I was surprised that the price difference wasn't bigger, in the 1-2 carat range it seemed the difference was maybe 10-20% or so, which is not nothing but not massive.

Could be an artifact of where I was looking however.