Are ab exercises the same as core strengthening exercises?
They're One Aspect of Core Training
Old Soviet Coaches have a saying: Strong Abs, Strong Back, Strong Hands.
Essentially your "core" or the area around your mid section consists of several groups of stabilizing muscles. They keep your spinal column in place while under heavy loads. This means vertebra doesn't move or movement is a very restricted.
Even though your spine has high tensile strength, it can be dislocated.