Site models include things like gamma rate heterogeneity and proportion invariable sites, so calling a substitution model a site model does not seem to be appropriate.
We agree on that. We have reworded accordingly.
[ ] Call a site model a site model and
a nucleotide substitution model a nucleotide substitution model
From response letter:
We agree on that. We have reworded accordingly.
a nucleotide substitution model a nucleotide substitution model