Infectious diseases (Communicable diseases): When a disease-causing organism enters our body it causes infection, it multiplies and grows in the body called host and micro-organisms multiplies in the host body.
Non-Infectious diseases (Non communicable diseases): Diseases that are not contagious are called non-infectious or non-communicable diseases because they can't be spread from one person to another. So, there's no vector for them to move from one host to another, no virus, no bacteria, no pathogen.
Instead, these diseases are caused by other factors, such as genetics, environment, and lifestyle behaviours.