A primary metabolite is typically present in many organisms or cells.
It is also referred to as a central metabolite, which has an even more restricted meaning (present in any autonomously growing cell or organism).
Note that primary metabolites do not show any pharmacological actions or effects.
A secondary metabolite is typically present in a taxonomically restricted set of organisms or cells (plants, fungi, bacteria, etc.).
Some common examples of secondary metabolites include: ergot alkaloids, antibiotics, naphthalenes, nucleosides, phenazines, quinolines, terpenoids, peptides and growth factors.