spirillum vs. spirochete

spirillum

[spahy-ril-uhm] / spaɪˈrɪl əm /

noun

Bacteriology.

spirilla

any of several spirally twisted, aerobic bacteria of the genus Spirillum, certain species of which are pathogenic for humans.
any of various similar microorganisms.

spirochete

[spahy-ruh-keet] / ˈspaɪ rəˌkit /

Or spirochaete

any of various spiral-shaped motile bacteria of the phylum Spirochaetes, distinguished by twisting flagella that run lengthwise between the bacterium’s inner and outer membranes, and inclusive of the family Spirochaetaceae, noted for certain pathogenic species that cause Lyme disease, syphilis, and other illnesses.