There've been many discussions on SO about the differences between (Rational) Unified Process and the Agile methodology. Can someone please give me an example on how different a project plan would be if there are 2 teams doing the same project, but following these 2 different methods?
I'm going to use Scrum as a concrete agile example. Scrum has three artifacts: the Product Backlog, the Sprint Backlog, and a Burndown Chart. A backlog is simply a prioritized list of things to do. The chart is for plotting your progress through the current sprint (iteration). These three tools are what you use to track and plan your project in Scrum and that is is your Scrum project plan.
RUP, on the other hand, contains a very long list of documents and artifacts for planning the project. As an example, there is the Iteration Plan, a detailed list of activities and tasks, with assigned resources and task dependencies. This document can perhaps be compared to the "sprint backlog" in Scrum, but that's stretching it.
So the major difference between these approaces is the amount of stuff (roles, artifacts, activities) they prescribe. And as you see from the image, the difference is huge:
I would say that RUP is totally different from Agile. RUP is a Model Driven code generation from UML diagrams which have previously captured the requirements. This is therefore a top down process.
Agile is a permanent top down, down top processes.
I would say that even if RUP is not used you can use UML with agile methodologies as long as your model could be automatically updated from your code. Omondo has done a big job on model iterations. PIM and PSM are syncrhonized. It means from the metamodel, to the model to the code and back in two ways. Really powerful and easy to use.
Agile methodology is based on the principle that any change in the iteration must cost the least to the developers. Thus changes from the customers are welcomed. Where as the Rational Unified Process is based on the principle that development of software must be such that changes are least. Thus RUP requires more experienced developers than Agile.