In most schools that I know, subject teachers can send the scores of students to the class teacher, but it is the class teacher who enters the results of his students into the gradebook. Actually, the class teacher keeps gradebook of students in his class.
Now is that the same way it is done in Gibbon? Is a subject teacher restricted to the entry of scores for the courses he teaches; and is it only a class teacher that can enter scores across all the subjects that a student in his class takes?
This is not a model I am familiar with, and not the way Gibbon works. In Gibbon, subject teachers can enter grades into the Markbook for their subjects, and the Class teacher (what we would call the Form Tutor or Roll Group Tutor) can view them. I am guessing with some creative use of roles, permissions, courses and classes, you could set it up the way you describe.
Subjects are all about teaching and learning, so they appear in the Planner, the Markbook, etc.
Form Groups are aimed at supporting student well being (what is called pastoral care in UK terminology), and so they are for taking attendance, monitoring behaviour, etc.
All this data ties together in the student profile, but comes from different sources.
No problem, I think the question is still answered above. The things listed in the two groups are what the two types of people involved (subject teachers, form tutors) can do. This is not an exhaustive list, just some examples.