There two initiative types to choose from, Standard or Agile.

Standard

A Standard initiative is the simplest way of managing the work week. Here are the key settings that are automatically applied when you create a Standard initiative: 
  • A work week of 7 days starting on a Monday is used to plan and manage work
  • A "Wishlist" tab is created in the Items & Tasks view to track and manage a list of deliverables that you are not able to get to in the current week, and do not wish to immediately plan to accomplish in the next several weeks
  • More powerful work management features such as Burndown, Points and Velocity, and Iteration Baseline are turned off by default. You can always turn any of these features back on from the Initiative settings page
Note: This is a good option if you want a simple work management tool. 

Agile

An Agile initiative is best suited for project management and agile PM gurus that want to have more flexibility and power from day one. You can define your work period to be 1 week, 2 weeks, 10 days, or any arbitrary length you choose. Also all of the agile project management features such as Velocity and baselining are enabled automatically - with even more power ready for you to activate using the Initiative settings page.

Note: If you are familiar with agile/scrum work management or are a power project management user then you can choose this option and configure the initiative to suit your specific requirements.