What makes up each TeX Live install-tl scheme?

Well, there always is the hard way:

Several schemes are available on TeXLive, e.g.

basic, context, full, and more

They are described in these files https://tug.org/svn/texlive/trunk/Master/tlpkg/tlpsrc/scheme-basic.tlpsrc?view=markup https://tug.org/svn/texlive/trunk/Master/tlpkg/tlpsrc/scheme-full.tlpsrc?view=markup https://tug.org/svn/texlive/trunk/Master/tlpkg/tlpsrc/scheme-context.tlpsrc?view=markup ...

These contain lists of dependent collections and packages, e.g. basic contains: depend collection-basic depend collection-latex

These, again, are files in the same folder: https://tug.org/svn/texlive/trunk/Master/tlpkg/tlpsrc/collection-basic.tlpsrc?view=markup https://tug.org/svn/texlive/trunk/Master/tlpkg/tlpsrc/collection-latex.tlpsrc?view=markup

Let's have a look at collection-basic: category Collection shortdesc Essential programs and files longdesc These files are regarded as basic for any TeX system, covering longdesc plain TeX macros, Computer Modern fonts, and configuration for longdesc common drivers; no LaTeX. depend texlive.infra depend amsfonts depend bibtex depend cm depend colorprofiles depend dvipdfmx depend dvips depend ec depend enctex depend etex depend etex-pkg depend glyphlist depend graphics-def depend hyph-utf8 depend hyphen-base depend hyphenex depend ifplatform depend iftex depend knuth-lib depend knuth-local depend kpathsea depend lua-alt-getopt depend luahbtex depend luatex depend makeindex depend metafont depend mflogo depend mfware depend modes depend pdftex depend plain depend tex depend tex-ini-files depend texlive-common depend texlive-docindex depend texlive-en depend texlive-msg-translations depend texlive-scripts depend tlshell depend unicode-data depend xdvi

As you can see we are now at the package level. The packages have, again, their own files in the same location:

The package latex-bin.tlpsrc contains this line: https://tug.org/svn/texlive/trunk/Master/tlpkg/tlpsrc/latex-bin.tlpsrc?view=markup#l29 binpattern f bin/${ARCH}/pdflatex

I am not an expert, but this looks to me like this package provides the pdflatex binary.

Resolving these dependencies is the job of the tlmgr-tool. According to Find needed package with tlmgr you should be able to find any specific file you are looking for. I am not sure that there is a way to list all the files that a package provides. Please keep in mind that not all the files that a package provides are necessarily contained in the package (they could be generated upon installation).

The TeXLive Manual actually recommends to install full.