One of the most basic guitar skills are strumming up and down freely. And I have noticed in songs that there usually appears to be a difference in sounds between the two strokes. But when I'm practicing I don't feel that difference between my strokes. My upstrokes and downstrokes sound more or less the same. Which brings me to my question.
What exactly is the difference between the two strokes, in general, apart from the fact that the pick goes in different directions? Do we alter pressure while doing upstrokes? Or do we trace a curved path touching only few of the strings each time for upstrokes and refrain from playing all the 6 strings? Or do we apply more pressure on the bottommost strings and less on the top ones?