ipamorelin vs sermorelin, they hit different receptors and everyone skips that
These get treated as two flavors of the same thing. They act on different receptors.
Sermorelin is a GHRH analog, GHRH(1-29). Works on the GHRH receptor, same pathway as your own GHRH.
Ipamorelin is a ghrelin receptor (GHS-R) agonist. Different receptor, different pathway. Usually described as selective, meaning comparatively little effect on cortisol and prolactin, which is the main thing separating it from older secretagogues.
Because they hit different receptors people talk about them together rather than as alternatives, on the logic that two pathways converging on the same output might do more than either alone. Reasonable logic, but it's inference.
Tesamorelin belongs in this conversation because it's the one with an actual approved indication (HIV associated lipodystrophy), so it's the only compound in this cluster with a real regulatory package behind it.
Rough evidence picture: tesamorelin approved for one specific thing, sermorelin has real historical clinical use, ipamorelin has development stage data and no approval.