@velikaratay
Q1: What is the difference of both? 
A: Goal: Any outcome that's going to require more than one item, in some sequence of tasks and projects in order to be able to achieve that outcome, that's a goal. Both tasks and projects can be assigned to a goal. Once added to a goal, tasks will go to Next by default. You can see all tasks/projects included the goal when you unfold it. In addition, you can complete all tasks/projects by completing the goal they belong to. 
Project: Every task can belong to a certain project. You can view all tasks with the same project by clicking to unfold the project, and by completing the project, you'll complete all the to-dos under it.
Goal is larger than Project, and it can contain Project. 
Q2: And how is the approach of both?
A: What do you mean by "the approach of both" ? Do you mean how could you create, edit or delete them? 
Goal: http://faq.doit.im/web.html#43
Project: http://faq.doit.im/web.html#34
Q3: When to use which of them?
A: Just I said in my first reply, Goal is larger than Project, and it can contain Project. For example, "Keep fit" can be regarded a goal. And you may assign a project like an exercise program to it. 
If you have further questions about it, please feel free to contact us.
Thanks for your support on Doit.im.
                        
Project vs. Goals
                  
                  1-What is the difference of both? 
2-And how is the approach of both?
3-When to use which of them?
                  2-And how is the approach of both?
3-When to use which of them?
- 
                  09/11/2013 02:22#1
PRO
 - 
                  09/22/2013 07:08#3
PRO
@velikaratay
If you have further questions about it, please restart a new ticket.
Thanks for your feedback and support. 
