One point that often causes confusion: in Brazil, ABNT adopts many of these international standards identically, publishing them under its own number. For example, ISO 9001 is adopted as NBR ISO 9001. They are not different standards; it is the same international standard, translated and formalized by ABNT. An “NBR” without “ISO” in the middle (such as NBR 6118, on concrete structures) is a genuinely Brazilian standard, with no international equivalent. Those are in the Brazilian Standards block.
This block brings together the most relevant international management standards for companies operating in Brazil, starting with ISO 9001 (quality management), with others, such as IATF 16949 (automotive quality) and ISO 14001 (environmental management), being added progressively.
If your company already follows an equivalent Brazilian standard, it is usually not necessary to implement the international standard in parallel. Which one to follow is usually set by the customer, the contract or the market the company operates in (exporting, for example, tends to require the international standard directly). An international standard, on the other hand, can be implemented and certified independently, without depending on any prior national accreditation.