The expressions 5 x (6 - 4) and 5 x 6 - 4 are different because....
Anything inside the parentheses has to be done first so 5 x (6 - 4) the 6 -4 has to be done first but in 5 x 6 - 4 you have to follow PEMDAS and do multiplication first.
Hope I helped!
-Char