AHK-Cu vs GHK-Cu — two copper peptides with very different amounts of research behind them
Both are copper-binding tripeptides. That shared chemistry is why they get shelved together, and it's about where the similarity ends in terms of what's actually been studied.
GHK-Cu has by far the larger literature — matrix remodelling, fibroblast activity, wound-healing work, plus the cosmetic studies. Still mostly in vitro and small topical trials, but there's volume.
AHK-Cu comes up almost entirely in hair contexts. The published base is much thinner and a lot of what circulates traces back to a small number of sources, some of them commercial rather than academic.
That asymmetry is the actual answer to "which is better studied" and it's rarely stated. People compare them as if the evidence bases were comparable in size. They are not — it's not close.
Happy to be corrected if someone has AHK-Cu sources I haven't found. That's partly why I'm posting.