From experience and not repeating the words of others, Samadhi is a controlled physical death. The breathing stops in Dhyana. Then, the heart in Samadhi. It is not good to describe the experience but rather the methods to get there, as knowing that to look for can prevent obtaining it. Extreme concentration causes it in conjunction with cutting the knots or cakkras which hold one locked in the body. A correct method is needed to ensure it, lahiri mahasaya's methods are good, as are the tantrik methods (more forcible and can cause health problems), which force the blood pressure low but bounces back. Cells oxygen starved long enough go anaerobic and can turn into cancer. Meditational methods put all the cells to stop and need no oxygen. Take a very scientific approach to getting samadhi as endless falsities and imaginations will try to pose as being it when they are just more mayic delusions. After samadhi you see through the endless lies of others, and the dream world we live in. People wrapt up in psychological universes and delusions. Before samadhi, we understand nothing. After, all answers are had with perfect self-evidence preventing any possibility of having had another fraud in the endless ocean of it within mayic delusion. Certainty. Pure, crystaline, unending, unassailable.
Enlightenment and satori are often confused. Samadhi towers above both. Satori is a breakthrough to higher levels. Enlightenment is the spiritual disaster, where the mind is done and one no longer lives in a belief system or reality tunnel based on one's limited perceptions and unproven beliefs. A buddha may speak truth, but it is only theory for anyone who hears it. Thus in enlightenment, nothing is true.
You have to die to get though the door. The little self opresses and prevents the real Self. But it isn't how you think, because if you knew who, or what, you really are, you would be enlightened already, and laughing at the sillyness of it all.
Best of luck and many blessings.