Original: ISO 3166-2:BR is the entry in ISO 3166-2, part of the ISO 3166 standard published by the International Organization for Standardization (ISO), which defines codes for the names of the principal subdivisions of Brazil (whose ISO 3166-1 alpha-2 code is BR).
Simplified: ISO 3166-2:BR is an ISO standard which defines geocodes: it is the subset of ISO 3166-2 which applies to Brazil.