In the comparison charts they line up their prepackaged servers with Amazon's and then compare price differences, often coming in lower than AWS. In one paragraph they make a note of this:
Note that configuration parameters for Azure instances
and AWS instances are not necessarily a perfect match,
e.g. Azure A5 instance provides similar compute power
with slightly less memory (Azure 14 GB RAM vs. AWS
17 GB RAM).
That's a ~17.6% difference, which is not so slight.
