Since you actually use the seed with corn, crosspollination can be a problem. Assume that they are growing on the same schedule and crosspollinate, then your popcorn won't pop and your sweet corn will not taste like sweet corn.

Corn, unlike most other vegetable crops, is affected by cross pollination in the current generation. Popcorn crossed with sweet corn, for instance, will produce poor popcorn and poor sweet corn.

If you are very lucky, they will pollinate at different times and will not cross. I would not count on being so lucky unless you are very familiar with their growth cycle and plan carefully.

The surest method is to bag the tassels and the ear sprouts and hand pollinate. I wont't detail that process here. You can find it by searching the web.

Jim