In dalālat al-naṣṣ, the understood meaning of the wording indicates a related ruling; for instance, a prohibition of slight verbal harm to parents plainly encompasses more severe harm with greater force.
Analogy, by contrast, requires establishing an operative cause in an original case and its occurrence in a new case, subject to the relevant conditions. Both can broaden application, but their routes of inference differ.
Diagnostic question: Does the conclusion follow from the linguistic force of the expression itself, or is an inferred common cause being established between an original and a new case? The answer changes the form of evidence and the objections available against it.