Timeline

Timeline is the genus; the Gantt chart is the species. A plain timeline puts events in order on a line — fine for a roadmap slide or a history lesson. A Gantt chart adds the machinery that makes a timeline into a plan: bars with real durations, and dependencies that connect them, so the picture can answer "what happens to the launch if design slips?"

The test is whether the pieces know about each other. If moving one event doesn't logically move any other, a simple timeline is enough — and simpler is better. The moment your plan contains the word "then" or "while," the events are connected, and a timeline that ignores those connections is a plan that will be wrong by Tuesday with no way to say how wrong.

Plenty of "timeline" slides in decks are secretly wishes: parallel bars, no arrows, every workstream conveniently finishing the week before launch. Drawing the dependencies is the difference between decoration and a plan.