Resin comes from the trichomes of the cannabis plant, which are tiny structures where cannabinoids like THC and CBD are produced. While both stems and buds produce resin, buds generally have a higher concentration of trichomes. This results in resin from buds being more potent and cannabinoid-rich. On the other hand, resin from stems contains these compounds too but at a lower concentration. So, while you can extract resin from both stems and buds, you might need more stems to match the potency of resin derived from buds.