The common thread throughout the above platforms is customer profiling and the data that they each use to build those profiles.
CDPs build profiles using first-party sources, namely the interactions that sales, marketing, and customer support teams have with customers. Data is also consolidated from customer interactions online, through social accounts, and email systems. But also offline transactional data is used, such as point-of-sales (POS) systems or loyalty cards. Then customer opt-in information found in CRMs, like names and addresses, can be matched to purchased goods which can be fitted together to present a fairly unified view of a customer. These views can be further leveraged into email campaigns, and remarketing. CDPs are highly granular, powerful, and beneficial for enterprises.
To contrast, Data Management Platforms (DMP), using third-party data, form customer archetypes rather than profiles. Because third-party data is anonymized and pre-segmented, customer identities are not available. DMPs are useful when marketers want to target specific audience segments to launch targeted campaigns.
MDM platforms and CDPs seem too similar because they aggregate data. And while there is overlap, CDPs primarily focus on features that sync data sources. The more encompassing MDM platforms that take in data from across all domains focus on record matching, transforming data, and singling out the common threads among domains to make all data in the organization usable as a single source of truth for the business.