"Righteousness" is spoken of in Romans, "sanctification" in Hebrews. The scene in Romans is the throne, and a righteous God; in Hebrews, the sanctuary and a holy God. In Romans the point is the guilt of the sinner; in Hebrews, his defilement, while with regard to the sacrifice of Christ (of which both speak) Romans sets before us its perfection as meeting the righteous claims of God, whereas in Hebrews we get its eternal character in being offered once for all on these two foundations our peace rests.
Christ's work must be perfect that we may have a standing at all, before a righteous God; it must also be of eternal efficacy that this standing may never be lost.