It might be easier to deploy the "advanced" LTE on that area due to geography, demand, etc. I'm just speculating.
It honestly doesn't make a big difference. LTE starts at 42 mbps (limit of HSPA+) and goes up to 75. I believe the "advanced" speeds are up to 150. So far I believe the highest in Canada can go all the way up to 250 for Rogers. But honestly, anything past 75 is just overkill. It's a point of diminishing returns. You won't see pages load much faster.