The contrast between clauses can be described at two levels: formal difference in their outward wording or construction, and semantic difference in the purpose of reporting, asking, commanding, or supplicating.
Different forms may express similar communicative functions, and two apparently declarative forms may serve different ones. Neither surface resemblance nor surface difference alone is a sufficient rhetorical test.
SituationBasis for analysis
Both form and force differDisjunction is readily apparent
Form matches but force differsUse context to identify the purpose
Form differs but force is relatedCheck the common semantic link and intended coordination