Memory

hi it says ı am usıng 4.6 gb and can use 7.9 gb and :

1. when ı am lookıng to my area about what ı am usıng and how much mg are they (from phone) its not 4.6 gb

2.when ı connected to my laptop it says 8.62 gb is free

so where is 7.9 and 8.62 ?

and what ı am usıng for 4.6 gb ?

someone can solve that situation about memory ?