Lower price with long-term commitment on Microsoft Azure is usually linked to Enterprise Agreement. AWS provides "reserved instances", with discounts based on length of commitment.
Now, Azure provides the same, with bonus that the reserved instances could even be canceled for a refund without need to sell them on martketplace like on AWS.
With AWS adopting "per second" pricing similar to AWS and GCP,
and commitments to Docker and Kubertnets by all providers,
there is some convergence of cloud technology...