A device is substantially equivalent if it has the same intended use as the predicate and either the same technological characteristics, or different technological characteristics that do not raise different questions of safety and effectiveness, with performance data demonstrating equivalent safety and effectiveness. FDA makes this call in the 510(k) review by comparing the new device against the chosen predicate, point by point. A 'not substantially equivalent' finding places the device in Class III by default, which usually means pursuing De Novo classification or a PMA instead.

Why it matters

Substantial equivalence is the legal foundation of the 510(k) pathway. FDA decisions hinge on careful predicate selection and side-by-side comparisons of indications, technology, and performance.

Common pitfalls

•Failing to select an appropriate predicate device can lead to significant delays or rejection of a 510(k) submission.
•Claiming substantial equivalence without robust side-by-side comparison data will result in FDA deficiencies.
•Assuming that minor technological differences will automatically be considered substantially equivalent without justification is a common mistake.
•Not adequately addressing new questions of safety and effectiveness raised by technological differences will prevent 510(k) clearance.

Sources

The 510(k) Program Guidance · FDA
European Commission - Medical Devices · European Commission
IMDRF Documents · IMDRF

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Why compare MedTech terms side by side?

MedTech terminology is full of pairs that look interchangeable but carry very different regulatory, clinical, and commercial consequences. Picking the wrong framework, pathway, or standard early in a project can add months to a submission, invalidate clinical evidence, or trigger an audit finding. Side-by-side comparison is the fastest way to surface those differences before they become costly mistakes.

Each comparison on this page pulls from the same vendor-neutral, sourced definitions used throughout the MedTech Terms glossary. You see the one-line summary, the formal definition, why it matters in practice, common pitfalls, and the primary sources (FDA guidance, EU MDR/IVDR articles, ISO/IEC standards, MDCG documents, IMDRF principles) that back each entry. That makes the comparison defensible in regulatory strategy memos, design reviews, and submission narratives.

Common comparison patterns

Regulatory pathway choice - 510(k) vs PMA, 510(k) vs De Novo, Abbreviated vs Special 510(k).
Quality systems - QSR vs ISO 13485, QMSR vs QSR.
Software classification - SaMD vs SiMD, Locked vs adaptive AI.
EU frameworks - MDR vs IVDR, CE Mark vs UKCA.
Cybersecurity artifacts - SPDX vs CycloneDX SBOM, CVE vs CVSS.
Post-market actions - Recall vs field action, Removal vs correction.

How to use this tool

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MedTech Terms is a vendor-neutral community resource sponsored by Blue Goat Cyber. Definitions are written for educational use and are not legal or regulatory advice.