The following is a very well-known classification of the different type of services offered by Microsoft for on-premises and the cloud. Microsoft Azure provides a full spectrum of services starting with Infrastructure as a Service (IaaS), followed by Platform as a Service (PaaS) and Software as a Service (SaaS) models such as Dynamics CRM, Office 365, and so on:
Service classification model
With IaaS, customers can deploy a virtual machine of their choice without the complexity of buying and managing their own hardware/software; they can quickly scale up and down with demand and pay only for what they use. This will reduce operational expenses of hosting and managing infrastructure.
Azure provides a vast range of PaaS services such as web apps, logic apps, media apps, API apps, mobile apps, Azure Stream Analytics, Azure HDInsight, and Azure Redis Cache. PaaS services like PowerApps are targeted at business users to create simple mobile apps and business workflows...