They do the same job. In England and Wales the court order that ends a marriage was called a decree absolute until 6 April 2022, when no-fault divorce came in and it was renamed the final order. Scotland issues an extract decree of divorce instead.
Japanese offices aren't fussy about the English name, but they do want the right document. A conditional order (formerly a decree nisi) is only the halfway point and doesn't end the marriage, so it won't do the job on its own. If you're not sure which you have, look for wording that the marriage "has been dissolved".
We translate whichever version you hold, along with the court seal, case number and any certification on the copy. The terminology is translated accurately rather than modernised, so a 2015 decree absolute stays a decree absolute in Japanese.