"-" functions differently in the two formulas. In ",-5", there is
nothing to subtract from, so "-" is the unary minus, i.e. it produces
negative 5. In "F4:H4-F3:H3" there is something to subtract from, so
"-" is the subtraction operator.
Multiple cells are referenced, so "F4:H4-F3:H3" is an array formula,
that will behave differently depending on whether you array entered
(Ctrl-Shift-Enter) the formula or not. If you did NOT array enter, then
"F4:H4-F3:H3" will return the single difference F4-F3, and MIN() of that
one number is itself. If you did array enter, then "F4:H4-F3:H3" will
return an array containing the 3 differences, and MIN() will return the
smallest of the 3 differences.
Jerry