Separate overlapping labels by the experience they promise rather than treating bookstore categories as rigid rules.
Action describes the engine
Action fiction is driven by urgent decisions, physical movement, pursuit, escape, rescue or direct confrontation. A thriller adds sustained uncertainty and threat; adventure emphasizes journey, discovery and testing environments. Many series combine all three.
Use appeal factors, not labels
A reader who says “action” may really want lean prose, capable protagonists, international settings, moral clarity or frequent reversals. Naming those factors produces better choices than debating whether a book belongs on one shelf or another.
Expect overlap
Espionage, crime, historical fiction, science fiction and fantasy can all carry an action structure. Treat the genre label as the doorway and the series pattern as the deciding information.
A practical test
Read the publisher description of the first book and ask what creates momentum: a chase, a mystery, a war, a quest, a disaster or a conspiracy. That answer often predicts the reading experience better than the marketing category.