Adherence and adhesion are usually distinguished in current use.
In spite of exceptions the tendency prevails to use adherence when mental or moral attachment and adhesion when physical attachment is implied.
- they gave their adherence to the cause of reform
- the adhesion of lung tissues to the pleura
Sometimes, however, adhesion is used in place of adherence when the writer feels that the physical connotations of the former will add emphasis.
- the iron force of adhesion to the old routine
— Arnold