The main difference in Gram (+)ve and Gram (-)ve bacteria resides in their

Explanation

Gram-positive bacteria have a thick layer of peptidoglycan in their cell wall, which retains the crystal violet stain used in the Gram staining technique. This thick peptidoglycan layer is responsible for giving them their characteristic purple color when viewed under a microscope. On the other hand, Gram-negative bacteria have a thinner layer of peptidoglycan and an additional outer membrane composed of lipopolysaccharides. The thinner peptidoglycan layer in Gram-negative bacteria does not retain the crystal violet stain, and they appear pink when counterstained with safranin in the Gram staining process.