Coherence, cohesion mean the quality or character of a whole all of whose parts cohere or stick together.
Coherence usually implies a unity of such immaterial or intangible things as the points of an argument, the details of a picture, or the incidents, characters, and setting of a story, or of material or objective things that are bound into unity by a spiritual, intellectual, or aesthetic relationship (as through their clear sequence or their harmony with each other); it commonly connotes an integrity which makes the whole and the relationship of its parts clear and manifest.
Cohesion more often implies a unity of material things held together by such a physical substance as cement, mortar, or glue or by some physical force (as attraction or affinity).
Cohesion may also be used of either material or immaterial things when the emphasis is on the process by which things cohere rather than on the resulting unity.