HCM sits one level above HR software in most vendor taxonomies. Where an HR information system holds the record, an HCM suite adds the processes around it and usually the payroll engine underneath. Dayforce, ADP and Workday are commonly described this way, and workforce management is normally a module inside a broader HCM platform rather than a separate purchase.
The phrase itself is contested. Treating people as capital to be managed reads badly to plenty of practitioners, and some vendors have quietly moved to “people platform” or similar. The category has not changed with the vocabulary.
HCM is worth distinguishing from workplace management, because the two get shortlisted against each other by mistake. HCM answers questions about people, hours and pay. Workplace management answers questions about desks, meeting rooms, visitors, parking and whether the space is worth its cost. Organisations usually run both, connected through the identity provider, with leave data flowing from the HCM side so the workplace side does not offer a desk to someone who is off.