Where an ATS manages people who have applied to a specific vacancy, a CRM manages relationships with people who might apply in future. It typically holds talent pools, such as past finalists or event attendees, and supports email campaigns, tagging and segmentation. A recruiter might keep in touch with runners-up from last year's graduate scheme and invite them to apply when a suitable role opens.
Building relationships in advance shortens time to fill when roles open and reduces reliance on paid advertising. The value depends on data quality and relevance, since outdated records and generic mass emails help nobody. Under data protection law such as UK and EU GDPR, personal data kept for future roles needs a lawful basis and a clear retention period, and candidates should know how to opt out.