I guess that at the simplest level, Defender for Cloud will help protect your Cloud (Azure) workloads (although it can also track and protect some outside resources) whereas Defender for Endpoint protects your devices (Windows clients, but also other platforms).
As part of Defender for Cloud, you can select Defender for Servers either at the Premium 1 (P1) or Premium (P2) level.
Then, Defender for Office 365 protects your Microsoft 365 data (Exchange mailboxes, SharePoint sites and Teams...), Defender for Identity protects your onsite Active Directory and Defender for Cloud Apps help track and protect your users when navigating the Internet.
I hope the above helps.