What is the difference between a hernia and a weak spot?

Hernia is weak spot: A hernia is a "weak spot" found where there is an opening in the middle of muscle tissues, allowing abdominal contents to pass through. The danger is that they may get stuck or "strangulated." in medical terms we call that "incarcerated." either way the concern is that the involved segment of bowel or omentum gets caught and loses its blood supply. This can be an emergency. See a doctor.

Spectrum of disease: A hernia is a hole in the abdominal wall through which intra abdominal contents can protrude, and appear as a lump under the skin. These holes sometimes start out with a thinning of the muscles, which is more typical for inguinal (groin) hernia. The weakness does not allow passage of abdominal contents, thus is not dangerous. It may however be a precursor for a hernia.