What is difference between virulent and Avirulent?

Virulent refers to pathogens that are capable of causing disease and often have mechanisms that enhance their ability to infect and harm the host. In contrast, avirulent refers to pathogens that do not cause disease or are less capable of doing so, often due to a lack of harmful traits or factors that allow them to evade the host's immune response. Essentially, virulent strains are harmful, while avirulent strains are benign or less harmful.