adherence / adhesion
Sticking to a principle versus sticking as a physical fact.
Use adherence for loyalty or conformity to a rule, belief, or plan: adherence to the protocol. Use adhesion for the physical bond between surfaces, and for the medical sense of tissues that stick together. Adherence is the word for people and policies. Adhesion is the word for glue, tape, and the body.
Examples
Use Adherence to the diet was uneven.
Use The label’s adhesion failed in the heat.
Avoid Adhesion to the diet was uneven.