"high reps" and "low reps" usually refers to intra-set reps, in other words, the amount of continuous reps you can do. this becomes relative: if you have weight on the bar, and can do 15 reps, its not heavy, by definition.
if you mean high reps as in high volume, many sets with high weight, i think there are intelligent discussions to be had there. but all humans exhibit a strength curve such that heavy weight and high reps is impossible by definition. if you are doing high reps, it isnt heavy. if it is heavy, you wont be able to do high reps.