It is good that they have a way of measuring coverage that is not strictly geographically based but since it is proprietary it is hard to actually know what it means.
Lte speeds are faster than Wifi due to the backhaul obviously, typically wireless carriers buy higher BW backhaul that wifi providers since wifi is free so they tend to skimp on that, in theory wifi can do about the same speeds as Lte from the air interface capability by itself.