If two expressions are similar in length and order but one letter changes identity, the figure differs from extra-letter jinās. The classification then depends in part on whether the substituted sounds have nearby or distant articulation points.
Muḍāriʿ jinās involves relatively close articulation, making the phonetic resemblance more immediate. Lāḥiq jinās concerns more distant consonants. The label muḍāriʿ here is rhetorical, not the grammatical term for an imperfect verb.
Identifying the differing consonant is only the first step; the relationship between its articulation and that of the corresponding consonant determines the more precise designation.