أو مختلفان
Or the two terms differ in kind.
With one sensory and one intellectual term, we have a mixed pairing. The source uses al-maniyyah wa-l-sabuʿ (death and a predator), and a contrasting pairing al-ʿiṭr wa-khuluq karīm (fragrance and noble character).
Comparing death to a predator presents an intellectually understood reality through a sensed model. Comparing fragrance to good character relates a sensory experience to an intellectual moral quality. The differing kinds of terms do not themselves invalidate the simile.