| S.N | Pili | S.N | Fimbriae |
| 1. | These are fine hair-like microfibers. | 1. | These are tiny bristle-like fibers. |
| 2. | These are longer than fimbriae. | 2. | These are shorter than fimbriae. |
| 3. | These are less in number. | 3. | These are more in number. |
| 4. | About one to ten pili are present in every cell. | 4. | About 200-400 fimbriae are present in each cell. |
| 5. | Only present in gram negative bacteria. | 5. | Both gram negative and gram-positive bacteria contain it. |
| 6. | These are made up of pilin protein. | 6. | These are made up of fimbrillin protein. |
| 7. | These are rigid in structure as compared to fimbriae. | 7. | These are less rigid than pili. |
| 8. | Plasmid genes govern the formation of pili. | 8. | Bacterial genes in the nucleoid are responsible for formation of fimbriae. |
| 9. | Helps in bacterial conjugation. | 9. | Helps in attachment or adherence to the surface of other bacteria. |
| 10. | These are thicker in structure. | 10. | These are thinner than pili. |
| 11. | Related to twitching motility especially type IV pili. | 11. | No association with motility. |
| 12. | Acts as receptors for some viruses. | 12. | No activity related to receptors. |
| 13. | Length ranges from 0.5-2 µm. | 13. | Length ranges from 0.03-0.14 µm. |
| 14. | Distribution is random on the surface of the cell. | 14. | Distribution is uniform or even throughout the cell.
|
| 15. | These are hollow tubular in structure. | 15. | These are solid in structure. |
| 16. | Bacteria like E.coli, N. gonorrhoeae, Pseudomonas, etc. contain pili. | 16. | Fimbriae having bacteria are Salmonella typhimurium, Shigella dysenteriae, etc. |
Image source: quora Image source: biologyease
References:
i) https://microbiologynotes.com/differences-between-fimbriae-and-pili/