The project management discipline has two predominant styles:
Waterfall
You only move to the next phase only when the prior one is complete –like a waterfall¹
This approach may be more suitable for low risk projects, simpler more predictable implementations
Agile
Agile approaches are based on an empirical control method –a process of making decisions based on the realities observed in the project.
With close customer involvement the Agile approach involves multiple iterations to deliver value sooner.
The focus is on people, communications, the product and flexibility.
Waterfall:
You don’t take possession of the house until the house is fully ready (Go Live)
Agile:
You move in earlier: when structure is safe, basic kitchen features, 1 bathroom and 1 bedroom are ready.
While living there, you keep adding spaces, functionality, etc until deemed finished.