Both Genotropin and Norditropin has same active ingredient namely Recombinant Somatropin which is an HGH. Norditropin has a total dosage of 10 mg while Genotropin has a12 mg. Pricing vise, Norditropin costs more than the Genotropin. The working of both the pen is the same. Both equally improves the growth hormone which increases testosterone for muscle building.