I've seen many charts of Smoke Point charts for cooking oils online. And, there all slightly different if not very different. Even MasterClass and SeriousEats seems to have their own versions (butter moves around). Perhaps, that's due to the particular quality of the manufactured oil they tested, but I'm not sure.
So, a lot of cooking websites indicate that the smoke point of an oil is when the oil burns and breaks down--which chemically speaking, isn't correct from my understanding. Sure, at the smoke point, some compounds inside the oil may have broken down already since they break down at temperatures below the smoke point, but the smoke point itself is not a direct indication of that breakdown, rather, that, if any breakdown at lower temperatures should happen, it already happened when you achieve the smoke point.
So, what is the smoke point then? For me, what I've learned is that its just the vaporization temperature for oils. Water that evaporates (vaporizes) is steam. Oil that evaporates (vaporizes) is smoke (because its smokey looking). Also, I'm assuming fats and oils with the longest fatty acid chains, chemically speaking, have higher smoke points.
But, also, there's this note on Wikipedia:
"Specified smoke, fire, and flash points of any fat and oil can be misleading: they depend almost entirely upon the free fatty acid content, which increases during storage or use. The smoke point of fats and oils decreases when they are at least partially split into free fatty acids and glycerol; the glycerol portion decomposes to form acrolein, which is the major source of the smoke evolved from heated fats and oils. A partially hydrolyzed oil therefore smokes at a lower temperature than non-hydrolyzed oil. (Adapted from Gunstone, Frank, ed. Vegetable oils in food technology: composition, properties and uses. John Wiley & Sons, 2011.)"