As nouns,
Klebs-Loeffler bacillus is a hyponym of
corynebacterium; that is, Klebs-Loeffler bacillus is a
word with a more specific, narrower meaning than
corynebacterium:
corynebacterium: any species of the genus Corynebacterium
Klebs-Loeffler bacillus: a species of bacterium that causes diphtheria