Explanation
These are two object types that milestones can be added to. Milestones are time-dependent actions that need to be completed within a certain period to achieve service level agreements (SLAs). Milestones can be added to work orders or cases using entitlement processes, which are timelines that include multiple milestones for each work order or case. Verified References: :
https://help.salesforce.com/s/articleView?id=sf.entitlements_milestones_overview.htm&type=5 :
https://help.salesforce.com/s/articleView?id=sf.entitlements_process_overview.htm&type=5