We have moved legacy Windows applications onto both AWS and Azure, sometimes for organizations in the same industry running nearly the same software. The question we hear most is "which cloud is better for this?", asked as if there is a correct answer we are keeping to ourselves.
Here is the answer. For Windows Server, SQL Server, and ColdFusion workloads, AWS and Azure both work, and the application will not notice the difference. Choose on three other things: who will operate the environment, what your SQL Server licensing costs on each platform, and where your identity and security tools already live.
Who will operate the cloud after the migration?
The platform your operator already runs is usually the right platform. Every cloud environment has an operator: your internal IT team, a managed service provider (MSP), or a partner like us. That team's existing skills weigh more than any feature comparison.
Say your company runs on Microsoft tooling, your users sign in through Entra ID, and your MSP builds everything with Azure runbooks. Choosing AWS then means retraining that team or running two operating models side by side. Both costs recur every month, and both outlast any price difference between the platforms. The reverse is also true. A team with AWS skills in-house needs a strong reason to put Windows servers anywhere else, and "it is Microsoft software" is not one. AWS says it has run Microsoft workloads since 2008.
Our field rule: when the operator is an MSP, the MSP's platform wins unless licensing overrules it. Fighting your own operator is a bad trade.
Does SQL Server licensing change the answer?
Sometimes, and licensing is the one place where a real cost difference between AWS and Azure lives. For most older Windows applications, the SQL Server licenses cost more than the servers they run on, so licensing rules move the total more than compute prices do.
Two terms matter. BYOL (bring your own license) means you move licenses you already own to the cloud instead of paying for them in the hourly price. License Mobility is the Microsoft Software Assurance benefit that permits some of that movement. The rules differ by platform:
- On Azure, Azure Hybrid Benefit discounts Windows Server and SQL Server when you hold licenses with active Software Assurance or qualifying subscriptions.
- On AWS, SQL Server licenses with active Software Assurance can move to shared EC2 instances through License Mobility. Windows Server cannot. The AWS Windows licensing FAQ says Windows Server BYOL runs only on EC2 Dedicated Hosts, with licenses bought before October 1, 2019.
These terms change, so check them against the current Microsoft product terms when you plan, not against a blog post (this one included). What matters is that someone runs the comparison for your actual SQL Server editions and core counts. We have seen that comparison decide the platform. We have also seen a skipped comparison cost more than the whole migration.
ColdFusion licensing does not favor either cloud. You bring your Adobe ColdFusion license to both. Confirm the edition and instance count against the target design before install week, and do the same for every other licensed component.
What stays the same on both clouds
The hard parts of a legacy migration are identical on AWS and Azure, which vendors rarely say. The work is the dependency inventory, the database move and its downtime window, DNS TTLs, and cutover order. It is the reporting tool that turns out to need one specific SQL Server version. It is testing by IP before the DNS change, and deciding how long the old servers stay up for rollback. Our CF2025 migration field checklist covers these, and no item on it changes with the cloud logo. The same holds after cutover for keeping admin access to your new cloud account.
Platform choice cannot buy you out of migration discipline. Migration discipline works on either platform.
One difference we do see in practice is at the edge. Some organizations arrive with a third-party CDN or web application firewall (WAF) that predates the cloud decision and fails in ways nobody can see into. Moving the edge to the same platform as the servers (CloudFront and AWS WAF, or Azure Front Door) gives you one set of logs and one support channel when requests go missing. It is optional. It is also often the cheapest reliability gain in the project.
How to decide in one meeting
Four answers on a whiteboard settle the platform question:
- Who operates the environment after go-live.
- What the SQL Server licensing comparison says for your real core counts.
- Where identity and security tooling already live.
- Whether an existing contract (MSP, Microsoft Enterprise Agreement, support agreement) is a real constraint.
In our experience the platform is clear by the second or third answer. Spend the rest of the meeting on the migration plan, because the plan decides success.
If you have Windows or ColdFusion applications headed for the cloud and want the licensing math and the migration plan done by a team that has run both, see our AWS and ColdFusion migration practices, or start a conversation.