Jeff's example is a good one... I think its the answer you're looking for. If you play the rhythm guitar part for "Sweet Child O'Mine" on your acoustic, no one is really going to recognize it as you strum through those D and G chords. But, if you incorporate the melody line into your playing, then people would. But you're no longer playing the guitar part for "Sweet Child O'Mine", you're playing a hybrid part that incorporates the melody as well as the rhythm.