What is a variant string? What is the difference between a primary string and a variant string?

A primary string is the main gTLD string being applied for or an existing gTLD. A variant string is generated by applying the Root Zone Label Generation Rules (RZ-LGR) to the primary string. Variant strings are considered the "same" by the script community as defined in the RZ-LGR. They are categorized as allocatable variant strings (can be applied for as gTLDs) and blocked variant strings (cannot be applied for as gTLDs). Together, the primary string and its respective variant strings make up a variant string set.