An impact rated window laminates sheets of glass to a tough clear interlayer, the same basic idea as a car windshield. Hit it hard enough and the glass may crack, but it stays bonded to the interlayer and the opening stays sealed. That seal is the whole game in a storm: once wind enters a house through a broken opening, pressure builds against the roof and walls from the inside.
Units sold as impact rated are tested against windborne debris standards referenced by the Florida Building Code, and products used in Central Florida carry Florida Product Approval. Orange County is not in the High Velocity Hurricane Zone, so Florida Product Approval governs here rather than Miami Dade approvals (WindLoad Solutions, Orlando requirements page).