“Interpretation as explanation emphasizes the discursive aspect of understanding: it points to the explanatory rather than expressive dimensions of interpretation. Words, after all, do not merely say something (though they also do this, and this is a primary movement of interpretation); they explain something, rationalize it, make it clear. One may express a situation without explaining it; expressing it is an interpretation, but explaining it is also a form of ‘interpretation’.” (p20)
Palmer expresses the difference and interconnectivity between interpretation and understanding. If interpretation is to be used in an explanatory form then it is using the aspect of understanding that needs to be expressed externally to others conversationally or even didactically.