What is the difference between a Wikipedia stub and a full article?

Stubs and full articles are different stages of the same article rather than different types. A stub is a short article, typically under 500 words, that covers the basic facts about the subject – what it is, when it was founded or born, where it is located, what it does or did – and is sourced enough to establish notability but not enough to support a full treatment. Stubs are tagged as stubs and explicitly marked as incomplete, with a maintenance template inviting expansion. A full article is comprehensive: developed sections covering the subject’s history, structure, key activities, and relevant context; multiple sourced sections; conformance to the Wikipedia Manual of Style; and breadth of coverage that matches the substance of the subject. For COI work, starting with a stub is sometimes the right call when the sourcing supports notability but not full development; the article gets created, the entity gets the Knowledge Panel benefit, and the expansion happens over time as more sources accumulate.