title: Azure Functions Host Instance vs VM Instance
body: <p>Is there a difference between Host Instance and VM instance when running an Azure Functions on a Dedicated App Service Plan? Because according to <a href="https://docs.microsoft.com/en-us/azure/azure-functions/functions-scale#app-service-plan" rel="nofollow noreferrer">this</a>, App Service Plan use existing VM instances. But in my Function App's Scale Out plan, I can see option to increase the instance count. According to <a href="https://docs.microsoft.com/en-us/azure/azure-functions/functions-scale#app-service-plan" rel="nofollow noreferrer">this</a>, it says that scaling will add new VM instance. But according to <a href="https://docs.microsoft.com/en-us/azure/azure-functions/functions-scale#how-the-consumption-and-premium-plans-work" rel="nofollow noreferrer">this</a>, a host instance is the full Function App instance.</p>
  <p>So, will increasing the instance count, spin up new VM instance under the App Service Plan? If not, then is that going to start a new function app instance on same VM instance if possible? Does Scaling mean different for different plans?</p>