5th graders are students, but not all students are 5th graders. In this case you would use a comma.
Persons are are citizens and citizens are persons. (again, this is in context of the full Article)
The difference is that not all persons are citizens.
All Citizens are persons. TRUE
YET
All persons are Citizens. FALSE
In my example of 5th Graders....
All 5th Graders get Ice Cream; all students get Popsicle.
If I had intended to say that all students get Ice Cream and Popsicle I would have written...
All students get Ice Cream and Popsicle. (no need for two clauses.)
All Fifth Graders are Students. True
YET
All Students are fifth graders. False
Do you see basic reasoning now?
