| Serial | Characteristics | Gram Positive | Gram Negative |
| 1 | Gram staining | Stained purple or blue color (color of primary stain, crystal violet) | Stained pink or red (Color of counterstain or secondary stain, safranin) |
| 2 | Thickness of cell wall | 20-30 nm thick | 8-12 nm thick. |
| 3 | Smoothness of cell wall | The cell wall is Smooth | The cell wall is wavy. |
| 4 | Layer of Peptidoglycan | contain multilayered Peptidoglycan, that’s why the cell wall is thicker as compared to gram -ve | contain single-layered Peptidoglycan, that’s why the cell wall is less thicker as compared to gram +ve |
| 5 | Presence of Teichoic Acids | Some Gram-positive bacteria contain Teichoic Acids. | Absent |
| 6 | Presence Periplasmic Space | Periplasmic Space is absent in gram-positive bacteria. | Periplasmic Space is present in gram-negative bacteria. |
| 7 | Outer Membrane | Outer Membrane is absent in gram-positive bacteria. | Outer Membraneis present in gram-negative bacteria. |
| 8 | Porins | Porins are absent in gram-positive bacteria. | Porins are present in Outer Membrane |
| 9 | Lipopolysaccharide (LPS) Content | Virtually None | Contain high amount of Lipopolysaccharide (LPS) |
| 10 | Lipid and Lipoprotein Content | Low concentration (acid-fast bacteria have lipids linked to peptidoglycan) | High concentration (because of the outer membrane) |
| 11 | Mesosomes | Mesosomes of gram-positive bacteria are Quite Prominent | Mesosomes of gram-negative bacteria are Less Prominent |
| 12 | Flagellar Structure | Flagellar of gram-positive bacteria contain 2 rings in basal body. | Flagellar of gram-negative bacteria contain 4 rings in basal body. |
| 13 | Toxin Produced | Gram-positive bacteria can produce Exotoxins. | Gram-negative bacteria can produce both Endotoxins or Exotoxins |
| 14 | Resistance to Physical Disruption | The resistance capacity of gram-positive bacteria towards physical disruption is high. | The resistance capacity of gram-negative bacteria towards physical disruption is low. |
| 15 | Cell Wall Disruption by Lysozyme | The cell wall of gram-positive bacteria can be disrupted by lysozyme. | In case of gram-negative bacteria, to disrupt the cell wall by lysozyme require pretreatment to destabilize outer membrane |
| 16 | Susceptibility to Penicillin and Sulfonamide | Gram-positive bacteria has a high Susceptibility to Penicillin and Sulfonamide | Gram-negative bacteria has a low Susceptibility to Penicillin and Sulfonamide |
| 17 | Susceptibility to Streptomycin, Chloramphenicol and Tetracycline | The Susceptibility to Streptomycin, Chloramphenicol and Tetracycline, of gram-positive bacteria, is low. | The Susceptibility to Streptomycin, Chloramphenicol and Tetracycline, of gram-negative bacteria, is high. |
| 18 | Inhibition by Basic Dyes | Probability is high | The probability is low. |
| 19 | Susceptibility to Anionic Detergents | Probability is high | The probability is low. |
| 20 | Susceptibility to Anionic Detergents | Probability is high | The probability is low. |
| 21 | Resistance to Drying | Probability is high | The probability is low. |
| 22 | Magnetosomes | Magnetosomes are Usually absent in gram positive bactera. | Magnetosomes are Sometimes found in gram negative bactera. |
| 23 | Morphologycal character | Gram-positive bacteria are usually cocci or spore forming rods. There are some exception such as Lactobacillus and Corynebacterium. | gram-negative bacteria are usually non-spore forming rod shpe. There is an exception : Neisseria. |
| 24 | Endospore formation | Some gram-positive bacteria can produce endospores during unfavorable conditions. | Usually endospores formation not found in gram-negaitive bacteria. |
| 25 | Pathogenicity | There are few pathogenic bacteria. | Most of the gram-negative bacteria are pathogenic. |
| 26 | Nutritional Requirements | The Nutritional Requirements of gram-positive bacteria is Relatively Complex. | The Nutritional Requirements of gram-negative bacteria is Relatively simple. |
| 27 | Susceptibility to Anionic Detergents | In gram-positive bacteria, the Susceptibility to Anionic Detergents is High | In gram-negative bacteria, the Susceptibility to Anionic Detergents is low. |
| 28 | Resistance to Sodium Azide | gram-positive bacteria are highly resistant to Sodium Azide. | gram-negative bacteria has low resistant property againt Sodium Azide. |
| 29 | Resistance to Drying | High | High |
| 30 | Examples | Some example of gram-positive bacteria are Staphylococcus, Streptococcus, Bacillus, Clostridium, Enterococcus, etc. | Some example of gram-negative bacteria are Escherichia, Salmonella, Klebsiella, Proteus, Helicobacter, Pseudomonas, etc. |
