What differentiates gram-positive bacteria from gram-negative bacteria?

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The most significant difference between gram-positive and gram-negative bacteria lies in their cell wall composition. Gram-positive bacteria have a thick layer of peptidoglycan in their cell wall, which stains purple with the crystal violet dye of the Gram stain. Gram-negative bacteria have a thinner layer of peptidoglycan, but they also have an outer membrane composed of lipopolysaccharides that makes them resistant to the crystal violet stain and takes up the counterstain of safranin, which produces a pink or red color. Therefore, gram-positive bacteria appear purple under the microscope, while gram-negative bacteria appear pink. Nutrient requirements, colony appearance, locomotion, and oxygen usage can vary widely within both gram-positive and gram-negative bacteria and do not provide a reliable basis for differentiation.

What Differentiates Gram-Positive Bacteria from Gram-Negative Bacteria