A statistical business register (SBR) plays a central part in a system of official economic statistics at a national statistics office.
A company register has a different purpose: protection, accountability and control of legal entities.
Countries use whatever data sources they seem relevant. E.g. they often integrate a company register in one form or another.
In EU a corresponding regulation define register contents:
United Nations Economic Commission for Europe provides Guidelines on Statistical Business Registers which describes the roles of the statistical business register.
European Commission provides a legal framework for business registers for statistical purposes.