The vendor comparison pages are all written from inside one of the four categories, which is why they all conclude that the category they are written from should be the centre of your architecture. Read four of them and you will have four incompatible architectures, each internally consistent.
The map below is written from outside all four.
Short answer: the DAM owns the asset, the PIM owns the product record, the CMS owns the page, and the ERP owns the transaction. For any disputed field, ask which of those four things the field describes. That resolves most of them outright, and the leftovers are worth arguing about properly because they are genuinely contested.
What each one is for
DAM. The visual and rich media object, and everything intrinsic to it. What the asset depicts, who made it, what rights attach, which version is current, how it renders for a destination. Digital asset management as a category covers more than this in practice, but the intrinsic-to-the-asset test is the useful one. The longer version is in what a DAM actually does.
PIM. Structured product information. Identifiers, attributes, variant structure, category placement, per-market copy, and channel completeness rules. Product information management exists because product data has hundreds of attributes across dozens of markets and a supply chain of contributors, and nothing else handles that shape well. See what a PIM actually does.
CMS. Page and component structure, and editorial content that is not about a product. Which components sit on which page, in what order, with what copy, published when. A content management system is a composition tool. Its record is the page, not the things the page references.
ERP. The transactional record. Stock, cost, purchase orders, suppliers, fulfilment, financials. Enterprise resource planning is upstream of everything above and is usually the system nobody in a marketing conversation wants to talk about, right up until someone asks where the cost price comes from.
The field map
Field by field, here is where authority usually lands.
The DAM owns: master files and renditions, what an asset depicts, creator and shoot data, licence terms and expiry, releases, approval state, colour profile, asset version history, default image description.
The PIM owns: SKU and GTIN, attributes and specifications, units, variant structure, commerce category placement, per-market product copy, channel rules, and the product-to-asset association.
The CMS owns: page and component structure, navigation, editorial copy that is not product copy, publication scheduling for pages, and the choice of which asset appears in which slot.
The ERP owns: stock levels, cost price, supplier and purchase data, fulfilment state, and the canonical existence of a product as a thing the business transacts in.
Two of those deserve emphasis because they get placed wrong most often. The product-to-asset association belongs in the PIM, not the DAM, because it is a fact about the product rather than about the photograph. The canonical product identity usually originates in the ERP, not the PIM, because a product exists as a purchasable thing before anyone writes marketing copy about it. Getting the second one backwards produces two competing definitions of what a product is, which is the problem master data management exists to solve and which you would rather not need.
The two genuinely contested boundaries
Most of the map is uncontroversial once written down. Two areas are not, and pretending otherwise wastes a lot of workshop time.
Alt text and image descriptions. The DAM’s claim is that the text describes the image and should be reusable everywhere the image appears. The CMS’s claim is that good alt text is contextual, and the same photograph legitimately needs different text on a category tile, a size guide and a press page. Both are correct.
The workable answer is two fields rather than one argument. The DAM holds a default description of what is depicted, which is intrinsic. The placing surface may override it, which is contextual, and the override is the exception rather than the norm. MDN’s guidance on the img element and the WCAG overview both support that reading: alt text serves the function of the image in context, and the context is not always known at asset level.
Product copy in the CMS. Marketing wants long-form product storytelling built as page components, with layout. The PIM wants product copy as structured fields so it can be syndicated. Both are legitimate needs and they are not the same content.
The rule that holds: copy that has to go to a channel other than your own site belongs in the PIM as a field. Copy that only ever appears on your own site, as part of a designed page, belongs in the CMS as a component. If a piece of copy has to do both, it is a PIM field and the CMS composes around it.
How many of these do you need?
Fewer than four, for most people, and the answer changes with catalogue shape rather than with company size.
- Under a few hundred products, simple attributes, one market. The CMS or the storefront platform can carry product data. Skip the PIM until attribute count or locale count makes it painful, which is usually somewhere around a thousand SKUs or three markets.
- One brand, one market, no third-party rights. The CMS media library may genuinely be enough and adding a DAM adds an integration without adding an answer.
- Any real inventory or fulfilment. You have an ERP whether you call it that or not, and its data will be authoritative for the transactional fields regardless of what your architecture diagram says.
- Multi-market, multi-channel, seasonal reshoots. You need all four and you need the boundary written down before any of them is bought.
What you should not do is buy a system to solve a problem another one owns. A DAM bought to fix product data will not fix product data. A PIM bought to manage images will manage them badly, in a schema designed for attributes. A CMS asked to be the product master becomes the thing you replatform away from. DAM vs PIM sets out the two-system version of the same decision.
What do you do when two systems both offer the same feature?
Three questions, in order.
- Which system holds the record this field describes? Licence expiry describes an image. Net weight describes a product. Component order describes a page. Stock describes a transaction. Most fields stop here.
- Which system’s users maintain it? A field maintained by cataloguers, placed in a system cataloguers never open, will be empty forever. Where question one leaves room, authority should follow the workflow.
- Which system can enforce it? Controlled vocabulary and validation in one, free text in the other, is not a real choice. Enforcement wins.
Write the answers into an ownership matrix and get it signed by the owner of each system. That single artefact prevents more integration rework than any other document in the programme, and it becomes the input to the integration design in wiring a DAM to a PIM and the operating discipline in single source of truth applied to product data.