The question usually comes from organisations that already bought one and are now being offered the other. The short answer: they answer different questions, and neither can grow into the other's role.
A CMDB answers operational questions. What runs where, what depends on what, and who gets the call when a server needs patching at three in the morning. Its unit of detail is the configuration item: servers, services, instances. Its truth changes daily, and its value lies in being machine-maintained.
An EA tool answers decision questions. Which three systems actually do the same thing, what supports the strategy and what does not, what should we retire before the contract renews, and what does it hit if we do. Its unit of detail is applications, capabilities and decisions. Its truth changes when the organisation decides something, not when an instance restarts.
The confusion arises because both contain a list of systems. But the lists have different owners, different cadence and different readers. Operations reads the CMDB daily. The executive team never opens it, and if they did, it would not make them wiser: a CMDB cannot say whether the portfolio supports next year's plan.
That does not mean choosing one. A well-kept CMDB is an excellent data source for an EA tool: it supplies what actually runs, and the EA layer adds what it means. If you have a CMDB with high data quality, you are closer to a usable portfolio overview than most.
When is the CMDB enough? When the questions you get are operational questions. The day the questions turn into renewals, consolidation or AI governance across the portfolio, what is missing is no longer the format. It is the decision layer.
Read on: The application landscape · Integrations · AI changes everything about application portfolio management
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