Athlete's foot and toenail fungus are both fungal infections, but they aren't the same thing:
Athlete's foot Athlete's foot typically affects the skin on the bottom of the feet and between the toes. It causes the skin to become red, itchy, and peel away. Anyone can develop athlete's foot, but it's particularly common in runners and those who play sports.
Toenail fungus Toenail fungus is a fungal infection that develops inside of one or more nails. It presents few symptoms at first. As the condition worsens, it causes your nails to become thick, brittle, discolored, and crumbly.
Athlete's foot and toenail fungus usually aren't serious. But if you have poor circulation due to diabetes or another medical condition, the infections can increase your risk of complications.