Milestones and Task Lists

Milestones and Task Lists

I have two questions I'm hoping the Zoho Community will be able to assist me with:
  1. What is the difference between a milestone and a task list? Seems like they are both ways to group tasks.
  2. Do you need to use milestones and task lists? What if I simply wanted to log my time to a few basic tasks?
Here is some more information.  For most of the projects I work on, I need to log my billable hours to a simple set of time sheet categories like the ones listed below:
  1. Project kickoff
  2. Fact finding / discovery
  3. Development of project deliverables
  4. Project transition and closeout
  5. General project management
  6. Travel

At this point in our company's evolution, we do not need to be so granular in the way we track time. Logging time to a set of categories like the ones listed above works for us... rather than developing a full list of all possible sub-tasks and grouping them into larger categories (i.e. task lists).

Essentially, I'm just trying to make sure that I wouldn't be missing out on any critical features in Zoho Projects if I decided not to use milestones or task lists. Thanks!!