  $\Delta$ isobar components in the nuclear many-body wave function are
investigated for the deuteron, light nuclei (${}^{16}O$) and infinite nuclear
matter within the framework of the coupled-cluster theory. The predictions
derived for various realistic models of the baryon-baryon interaction are
compared to each other. These include local ($V28$) and non-local meson
exchange potentials (Bonn$_{2000}$) but also a model recently derived by the
Salamanca group accounting for quark degrees of freedom. The characteristic
differences which are obtained for the $N\Delta$ and $\Delta\Delta$ correlation
functions are related to the approximation made in deriving the matrix elements
for the baryon-baryon interaction.
