A milestone is a zero-duration checkpoint marking a point in time. A deliverable is a tangible artefact (doc, prototype, app) produced at or around a milestone. They co-occur but are not the same thing.
Key facts
Milestone: an event (start, end, phase boundary, review gate). Takes zero time.
Deliverable: an artefact (PMP, requirements spec, design doc, test plan, prototype, final app).
A milestone often signals delivery of a deliverable.
Milestones vs Deliverables
Milestones
Mark specific points along a project timeline
These points may signal anchors such as
A Project start and end date
Need for external review
Start and end of a phase
Completion of a deliverable
Deliverable
Specific artifacts that are of interest
Examples include
Project documnets such as the PMP, Requirements Specification, Design Document, Test Plan etc.