01 · SKUIs a SKU globally unique?
No. Different sellers can use different SKUs for the same item.
NOKnowledge hub · comparison
SKU vs MPN vs GTIN vs OEM Number
Four identifiers, four different owners. Who assigns each one determines where it can be trusted.
They are complementary, not interchangeable. A clean product record keeps each one in its own field and preserves the relationships between them.
SKU · SELLERInternal referenceSpecific to one organization.
MPN · MANUFACTURERManufacturer referenceProduct/model within manufacturer context.
WHO ASSIGNS IT?Ownership determines trustRole · scope · matching value
GTIN · STANDARDS-BASEDTrade identificationIdentity across systems and commerce workflows.
OEM NUMBER · OEMOriginal part referenceCritical in spare-parts relationships.
SKU
A SKU belongs to the organization using it
A SKU is an internal identifier used by a business to distinguish products inside its own catalog, inventory or order workflow.
Another seller can use a completely different SKU for the same physical product. That makes SKU useful internally, but weak as the only signal for external product research.
DISTRIBUTOR ASame physical product
SKU-483028DISTRIBUTOR BSame physical product
BRG-42-0020ONLINE RETAILER CSame physical product
900117-REDSame item, three internal references — none of them is globally portable outside its own organization.
MPN
An MPN connects a supplier record to the manufacturer’s own naming
An MPN is a manufacturer-facing product reference. In a technical catalog it can help connect a supplier record to the manufacturer’s own naming and documentation.
It should still be used together with manufacturer context, because the same-looking code can be ambiguous when brand information is missing.
"12345-A"Manufacturer XRESOLVED"12345-A"Manufacturer YRESOLVED"12345-A"(brand missing)AMBIGUOUSMPN12345-A
Manufacturer X
Manufacturer Y
Brand missing
GTIN
A standardized identity outside one seller’s SKU system
GTIN is used as a trade-item identifier across commerce and data-exchange workflows. Its value is providing a standardized product identity beyond one seller’s internal SKU system.
TRADE ITEMCommerce / data exchangeStandardized identity can travel across systems.
OUTSIDE THE SKUBeyond one seller’s namespaceUseful when seller-specific SKUs are not portable.
GTIN
FOUND
FOUND
COVERAGE GAPLegacy parts may lack GTINTechnical and older spare parts may have no usable GTIN in the source record.
A robust workflow cannot assume a GTIN exists. Matching must fall back to other identifiers plus context.
OEM number
Buyers search by the original reference even when the sold product is not the OEM item
An OEM number is the original equipment manufacturer’s reference for a part or component. In spare-parts catalogs it often becomes a key relationship field.
An OEM number can identify the original part, while an aftermarket record may represent an alternative or compatible item rather than the same commercial product.
OEM NUMBEROriginal referenceReference assigned by the original equipment manufacturer.
ORIGINAL PARTOEM identityMay be the actual original commercial part.
AFTERMARKET RECORDRelationship, not identityCan reference the OEM number without being the same product.
BUYER SEARCHReference-driven discoveryUsers may search the OEM number to find compatible alternatives.
Examples
One record can legitimately carry several identifiers at once
A single spare-part record can hold SKU, MPN, GTIN and OEM references simultaneously.
They should not be collapsed into one generic “product code” field because each identifier serves a different purpose. Not every public record exposes every identifier: the AC820825 reference record has no verified seller SKU, while its manufacturer reference and EAN are available.
SKUInternal seller fieldNot present in public source record
MPNManufacturer fieldAC820825
GTINTrade-item field8716106986118
OEM REFERENCERelationship fieldAC820825 · original-part reference
skuInternal identifierCatalog / inventory workflowmpnManufacturer referenceManufacturer context / researchgtinTrade identifierCross-system identity when availableoem_referenceOriginal part relationCompatibility / cross-reference contextRelationships between identifiers
Keep each identifier in its own field and preserve the relationship
A practical product record preserves the relationship between the sold product, the manufacturer reference and any OEM or cross-reference data.
INPUT RECORDSeveral codes are presentSKU, MPN, OEM reference and optional GTIN arrive with different ownership.
Same product
Original part
Alternative relationship
IDENTITY RESOLVERWhat relationship do these codes express?
STRUCTURED RESULTIdentity + relationshipsThe product record keeps each field separate and records the link explicitly instead of treating every code as a synonym.
Spare-parts cases
A distributor record can hold four codes with four different owners
A distributor may sell its own SKU, receive a supplier code, reference a manufacturer MPN and also list one or more OEM numbers used by buyers to find the right part.
Compatibility, replacements and aftermarket cross-references are separate relationships that require their own validation.
FIELDOWNERROLE
seller_skuDistributorInternal commercial recordsupplier_codeSupplierSupplier-side referencempnManufacturerManufacturer product referenceoem_referenceOEMOriginal part relationshipCOMPATIBILITY
REPLACEMENT
AFTERMARKET CROSS-REF
Matching problems
Four ways identifier matching goes wrong
Common problems appear when a code loses its context, changes shape between sources or is mistaken for a different kind of reference.
01Manufacturer context removed
02Separators or prefixes change
03Reference type misclassified
04Relationship mistaken for identity
INPUT
12345-ACONTEXT
CHECK
CHECK
LOST CONTEXTUnsafe matchThe same-looking code can belong to several brands.
FAQ
Common questions about product identifiers
Four questions about uniqueness, MPN versus OEM, multiple identifiers and which one to research with.
02 · MPN / OEMIs an MPN the same as an OEM number?
Not necessarily. The relationship depends on product and manufacturer context.
NOT NECESSARILY03 · MULTIPLE IDSCan a product have several identifiers?
Yes. SKU, MPN, GTIN and OEM references can coexist in separate fields.
YES04 · RESEARCHWhich identifier is best for product research?
There is no universal answer. Strong matching combines identifiers with manufacturer and technical context.
USE THEM TOGETHERKeep reading