The two terms get used interchangeably in vendor marketing, which causes real confusion. Document AI is the umbrella: any system using AI to read, understand, or generate insight from documents. Intelligent Document Processing is the specific, production-oriented practice inside that umbrella, extracting, classifying, validating, and routing data from documents into a business system.
Why the distinction is worth keeping
A Document AI capability might also cover things IDP does not focus on directly, summarising a long contract, answering a question about a document's content, or comparing two versions of a filing. IDP specifically is about turning a document into structured, validated data a downstream system can act on. If a vendor pitches "Document AI" without being able to say which specific extraction and validation steps their system actually performs, that is worth pressing on.