Answer 1

A variable declared on the heap uses the heap memory. (idk how else to put that)

A variable declared globally is declared outside a function, which can be accessed in any function of that class.
So, one refers to memory location, the other refers to access.

Quote from StackOverFlow:
"Global variables have static storage duration. They are stored in an area that is separate from both "heap" and "stack". Global constant objects are usually stored in "code" segment, while non-constant global objects are stored in the "data" segment."