The SN201 only has T and H-rated sizes, no V's like the SN250 has in some sizes.
Also, for 205/65-15, the SN250's treadwear rating is only 580, compared to 620 for every other size the SN201 comes in. And for this same size, the SN201 is H, while the SN250 is T
The SN201 seems like a cheaper alternative to the SN250, in addition to, not instead of the SN250. Kind of like Cooper's CS3 and CS5 lines.
I love the Ziex ZE950's I have on my car. They're awesome