Peptides and exosomes are fundamentally different types of biological molecules — one is a chain of amino acids, the other is a tiny membrane-bound package.
What it is
A chain of amino acids
A lipid membrane-bound vesicle (30–150nm)
Contents
Just the amino acid chain itself
Cargo: proteins, RNA, lipids, metabolites
Function
Direct signaling molecule
Delivery vehicle for cell-to-cell communication
Size
~1–5 nanometers
30–150 nanometers (much larger)
Synthesis
Chemical or ribosomal
Released from cells via endosomal pathway
Composition
Amino acids only
Lipid bilayer enclosing diverse cargo