On post-critically finite self-similar sets, whose walk dimensions of diffusions are in general larger than 2, we find a sharp region where two classes of Besov spaces, the heat Besov spaces
$B^{p,q}_\sigma (K)$ and the Lipschitz–Besov spaces
$\Lambda ^{p,q}_\sigma (K)$, are identical. In particular, we provide concrete examples that
$B^{p,q}_\sigma (K)=\Lambda ^{p,q}_\sigma (K)$ with
$\sigma>1$. Our method is purely analytical, and does not involve heat kernel estimate.