||These are helical structures but are not straight.
||These are non-helical structures but are straight.
||These are long whip like filamentous structures.
||These are short hair like, filamentous, and tubular microfibers.
||Comparatively thicker than pili.
||Comparatively thinner than flagella.
||Diameter of flagella is 10-30 nm.
||Diameter of pili is 3-10 nm.
||Occur in different forms in the cell like lateral, peritrichous and polar.
||Occur throughout the entire surface of the cell.
||Presence noticed in both gram positive and gram negative bacteria.
||Presence noticed in only gram negative bacteria.
||Flagellin protein is their main content.
||Pilin protein is their main content.
||These structures arise from cell wall.
||These structures arise from cytoplasmic membrane.
||These are bacterial, archaeal and eukaryotic type.
||These are conjugative and type IV in types.
||Provide motility to the cell and sometimes act as sensory organ.
||Provide attachment or adherence to the other cell for conjugation process.
||Generally show undulating and sinusoidal motion.
||Generally show twitching motility mostly by type IV pili.
||Number is less as compared to pili.
||Number is more compared to flagella.
||Origin is interior.
||Origin is external.
||About 5-20 µm in length.
||About 0.3-1.0 µm in length.
||Genes present in nucleoid region controls their formation.
||Gene present in plasmids controls their formation.
||These are more rigid than pili.
||Comparatively less rigid than flagella.
||No role in genetic exchange between the organisms.
||Sex pili through conjugation tube transfer the genetic materials.
||Do not function as receptors to any viruses.
||Function as receptors to some viruses.
||A complex motor system is present for propulsion at the base.
||This motor system is not present in pili.
||E. coli, Salmonella, Campylobacter, Helicobacter, Enterococcus, Listeria, etc. bear flagella.
||E. coli, N. gonorrhea, Pseudomonas, Salmonella, Shigella, etc. bear pili.
Image source: microbiologynotes
Differences between Flagella and Pili