A storm door is usually constructed from heavier materials, like tempered glass and aluminum, that allow it to better protect your home from the elements. It may have sturdier hardware and hinges that enable it to stand up to storms and high winds. Some storm doors also have the option to incorporate a deadbolt-style lock for additional security. If you have pets, you can have a pet door installed in a storm door. 

Screen doors may be constructed from wood or aluminum and offer some protection for your home. However, they usually use lightweight hardware and are lighter overall than storm doors. While some screen doors do have a lock on them, they don’t have the option to install a deadbolt-style lock.