A change in syntactic case and a shift of lexical meaning are different scholarly questions. Both may arise in a single sentence, but their definitions and analytical tools are distinct. The first tracks governors, annexation, subjects, and objects; the second tracks meaning, relation, and contextual evidence.
“Ask the town” requires understanding that the inhabitants are intended, but the grammatical analysis additionally explains why “al-qaryata” appears in the accusative. In “laysa ka-mithlihi shayʾ,” the status of kāf yields different rhetorical accounts of the same intended negation.
Recognizing these distinctions allows a broader understanding of the term majāz without reducing all its uses to a single rule.