biblatex approach to bibliographies is very different from that used by 'traditional' BibTeX, which includes
natbib. The way that a traditional style works is that BibTeX-the-program reads the
.aux file (for citations),
.bib file (for data) and
.bst file (for style), and write a
.bbl file containing the formatted output. The latter is then typeset directly in LaTeX (i.e.
\bibliography is a special form of
\input). When using
biblatex, in contrast, citation data (from the
.bcf) is used along with the
.bib file to give a database-like
.bbl file. The latter is used by
biblatex to do formatting at the LaTeX end (i.e. in LaTeX macros). In this cases, formatting is driven by a
.bbx file, which tells LaTeX (not BibTeX) how to do the style. The two approaches are thus fundamentally different.
It is possible to write a
.bbx file which does the same as any given
.bst. Thus as well as the standard
biblatex styles, there are styles available which match the BibTeX 'traditional' set. There are also implementations for some journal styles. Included in those is
biblatex-phys, which implements the AIP and APS styles. As those can never be used with
natbib, and thus not with REVTeX, they are not official and cannot be used to substitute in journal submission. (See Is biblatex compatible with RevTeX?.) (Note that one can 'unload'
natbib as discussed in Is it possible to load biblatex with a class that has already loaded natbib?, but this would be a bad idea in any official submission.)