These are simply categorized by how many amino acids they contain — 2, 3, or 4.
Feature
Dipeptides
Tri/Tetrapeptides
Amino acids
2 (dipeptide)
3 (tri) or 4 (tetra)
Peptide bonds
1
2 (tri) or 3 (tetra)
Examples
Carnosine, Anserine
Tri: KPV, GHK-Cu | Tetra: Epithalon, SS-31
Bioregulators
Few dipeptide bioregulators
Many Khavinson bioregulators are tri/tetrapeptides
Oral absorption
May cross gut barrier more easily
Small enough for potential oral absorption research