If you grow your own corn, when it is ripe, you pick it, shuck it, boil it and serve with butter, salt and pepper. Some hold the cob with both hands, some cut the fernels off. What you will be eating is sweet corn.
If you let the corn stay on the stock and let it keep growing under the sun, the kernels will get bigger and will taste more like eating starchy carbohydrates, than the pleasantness of just ripe for boiling and eating, corn. So this next period of the growth of the corn is not considered sweet corn, but it is getting ready to be used as pig and horse feed.
Aged corn is not juicy. Sweet corn is.