# Changes in Windows Server AMIs by OS version
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AWS provides AMIs for Windows Server 2016 and later. These AMIs include the following high-level changes between AWS Windows AMIs for different Windows operating system versions:

## Windows Server 2025
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+ Windows Server 2025 AMIs use UEFI boot mode by default, except for Windows Server 2025 AMIs named `BIOS-Windows_Server-2025-English-Full-Base`.
**Note**  
EC2 metal instance sizes and some EC2 instance types do not support UEFI boot mode for Windows Server. To launch Windows Server 2025 on these instances, you must use the AWS managed `BIOS-Windows_Server-2025-English-Full-Base` AMI, or an AMI that is based on that image. For more information about UEFI requirements, [Requirements for UEFI boot mode](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/launch-instance-boot-mode.html) in the *Amazon EC2 User Guide*.
+ Windows Server 2025 AMIs support Nitro EC2 instance types only.
+ Windows Server 2025 AMIs use `gp3` EBS volume types by default.
+ Windows Server 2025 AMIs use the AWS.Tools PowerShell module.

## Windows Server 2016-2022
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+ To accommodate the change from .NET Framework to .NET Core, the EC2Config service has been deprecated on Windows Server 2016 AMIs and replaced by EC2Launch. EC2Launch is a bundle of Windows PowerShell scripts that perform many of the tasks performed by the EC2Config service. For more information, see [Configure a Windows instance using EC2Launch](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2launch.html). EC2Launch v2 replaces EC2Launch in Windows Server 2022 and later. For more information, see [Configure a Windows instance using EC2Launch v2](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2launch-v2.html).
+ On earlier versions of Windows Server AMIs, you can use the EC2Config service to join an EC2 instance to a domain and configure integration with Amazon CloudWatch. On Windows Server 2016 and later AMIs, you can use the CloudWatch agent to configure integration with Amazon CloudWatch. For more information about configuring instances to send log data to CloudWatch, see [Collect Metrics and Logs from Amazon EC2 Instances and On-Premises Servers with the CloudWatch Agent](https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/Install-CloudWatch-Agent.html). For information about joining an EC2 instance to a domain, see [ Join an Instance to a Domain Using the `AWS-JoinDirectoryServiceDomain` JSON Document](https://docs.aws.amazon.com/systems-manager/latest/userguide/walkthrough-powershell.html#walkthrough-powershell-domain-join) in the *AWS Systems Manager User Guide*.

**Other differences**

Note the following additional important differences for instances created from Windows Server 2016 and later AMIs.
+ By default, EC2Launch does not initialize secondary EBS volumes. You can configure EC2Launch to initialize disks automatically by either scheduling the script to run or by calling EC2Launch in user data. For the procedure to initialize disks using EC2Launch, see "Initialize Drives and Drive Letter Mappings" in [Configure EC2Launch](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2launch.html#ec2launch-config).
+ If you previously enabled CloudWatch integration on your instances by using a local configuration file (`AWS.EC2.Windows.CloudWatch.json`), you can configure the file to work with the SSM Agent on instances created from Windows Server 2016 and later AMIs.