

Including what to confirm with Microsoft before you compare anything.
Microsoft has been consolidating it into the newer Planner experience, so what used to be evaluated as Project for the Web is increasingly sold as a paid Planner tier. Before comparing features with anyone, it is worth confirming with your Microsoft account team which product you are actually being offered.
Project for the Web and its successor are project-level tools: schedules, tasks, boards and assignments. PPM Express is the portfolio layer above them — objectives, investment categories, funding, weighted scoring, capacity across the organization, financials and benefits. They answer different questions, and are frequently used together rather than instead of each other.
PPM Express connects to Microsoft Planner, Microsoft Project Desktop and Microsoft Project Online. As Microsoft’s project tooling consolidates, confirming which of those your tenant actually uses is the practical first step in any evaluation.
When you need project scheduling rather than portfolio governance, and it already sits inside your Microsoft agreement. That is a real commercial advantage and should not be given up lightly. The portfolio question tends to arrive later — usually when someone asks how thirty projects compare, or which of them are worth funding next year.
Partly, and PPM Express is built for exactly that estate — Microsoft 365 SSO, a Teams app, Power Platform and Power BI connections, and connectors to Azure DevOps, Project and Planner. Staying inside the Microsoft world does not require the portfolio layer to be a Microsoft product; it requires it to work properly with one.