To start with, both amphibians make up the order Anura in the animal kingdom, but there are some key differences in the critters themselves. You can tell most toads and frogs apart by the appearance of their skin and legs. Most frogs have long legs and smooth skin covered in mucus. Toads generally have shorter legs and rougher, thicker skins.
As to the eggs you might be seeing in your Oklahoma pond, toads generally lay their eggs in very long strands of clear jelly, sort of like small black pearls in a long clear plastic tube (dish on right). Frogs, on the other hand, lay their eggs in a cluster that resembles a bunch of grapes (dish on the left).