As nouns,
Diplococcus pneumoniae is a hyponym of
diplococcus; that is, Diplococcus pneumoniae is a
word with a more specific, narrower meaning than
diplococcus:
diplococcus: Gram-positive bacteria usually occurring in pairs
Diplococcus pneumoniae: bacterium causing pneumonia in mice and humans
Other hyponyms of diplococcus include
pneumococcus.