here's a page that pretty thoroulghly illustrates the appearance of the two https://www.myfearlesskitchen.com/difference-between-sweet-corn-and-field-corn/ when just talking about mentions of corn in data sets, it's harder to say. I only really know cause I live here. Most of the corn in the supermarkets starts showing up while the local corn is still growing. I'm not entirely sure where it's imported from.