[qwertyuiop_]

If we stick to strict Project Management definitions, milestones are within a project.

A program (representing a strategic goal) can contain multiple projects big and small. Perhaps the author wants to convey programs which map to company or divisions strategic initiatives.

[siva7]

Which would be represented in OKRs. Honestly this article feels like using project management definitions without understanding where they are coming from.

[jaderubick]

I’m the author. No, not intending programs. Milestones are smaller than projects in my definition.