Merge pull request #193473 from ju-shim/update-328

VMSS Upgrade Policy and Automatic OS Upgrade settings

Author: PRMerger4

articles/virtual-machine-scale-sets/virtual-machine-scale-sets-automatic-upgrade.md

@@ -1,8 +1,8 @@
 ---
 title: Automatic OS image upgrades with Azure virtual machine scale sets
 description: Learn how to automatically upgrade the OS image on VM instances in a scale set
-author: mamccrea
-ms.author: mamccrea
+author: ju-shim
+ms.author: jushiman
 ms.topic: conceptual
 ms.service: virtual-machine-scale-sets
 ms.subservice: automatic-os-upgrade
@@ -124,6 +124,9 @@ Automatic OS image upgrade is supported for custom images deployed through [Azur
 ## Configure automatic OS image upgrade
 To configure automatic OS image upgrade, ensure that the *automaticOSUpgradePolicy.enableAutomaticOSUpgrade* property is set to *true* in the scale set model definition.
 
+> [!NOTE]
+> **Upgrade Policy mode** and **Automatic OS Upgrade Policy** are separate settings and control different aspects of the scale set. When there are changes in the scale set template, the Upgrade Policy `mode` will determine what happens to existing instances in the scale set. However, Automatic OS Upgrade Policy `enableAutomaticOSUpgrade` is specific to the OS image and tracks changes the image publisher has made and determines what happens when there is an update to the image. 
+
 ### REST API
 The following example describes how to set automatic OS upgrades on a scale set model: