The course is organized week by week, with a clear start date and a finish date. Moodle will create a section for each week of your course. You can add content, forums, quizzes, and so on in the section for each week.
TIP: If you want all your students to work on the same materials at the same time, this would be a good format to choose.
NOTE: Make sure your course start date is correct. If it is not your weeks will have the wrong date on it. This is especially important if you are restoring a course to use with a new section of students.
The course is organised into topic sections that a teacher can give titles to. Each topic section consists of activities, resources and labels.
TIP: This is great to use if your course is objective based and each objective may take different amounts of time to complete. An example of this would be scaffolding where the students are building upon the knowledge from earlier topics.
Topics do not have to be numbered and can be renamed using editing options on the course homepage.
"Show only one section"
With the Weekly format and the Topics format it is possible via Settings > Course administration > Edit settings to "show one section per page". Here is a course with three topics, with the second one currently shown. The links left and right lead to topics 1 and 3:
Notes:
This format is oriented around one main forum, the social forum, which appears listed on the main page. It is useful for situations that are more free form. They may not even be courses. The Moodle Lounge is an example of a social format course.
The social forum can be edited by clicking the 'Update this forum' button on the social forum page. The forum introduction is displayed at the top of the course page.
The SCORM format only has 1 section, and allows teacher to insert a pre-built SCORM package. Moodle can use SCORM packages as a content type (see SCORM module), or as a course format.
Note: If you have a large SCORM object you want to use as an entire course, then you can select this course format and students will only be able to interact with the SCORM object, not the rest of the Moodle tools.