Form and content

In art and art criticism, form and content are considered distinct aspects of a work of art. The term form refers to the work's style, techniques and media used, and how the elements of design are implemented. Content, on the other hand, refers to a work's essence, or what is being depicted.

Incongruity between form and content can be humorous

Form is one of the most frequent terms in literary criticism.it is often used merely to designate a genre or for patterns of meter lines and rhymes.

...
Wikipedia