Differences between XeLaTeX and LuaLaTeX embedding fonts (with optical sizes) in PDF

Question

Using TexLive 2014 (updated today) on Windows 7 the following code compiles using XeLaTeX and LuaLaTeX:

\documentclass{article}
\usepackage{fontspec}

\setmainfont[
Extension = .otf,
Path=otf/,
UprightFont = {*},
ItalicFont = {*-Italic},
BoldFont = {*-Bold},
BoldItalicFont = {*-Bold-Italic},
UprightFeatures = {%
    SizeFeatures={%
        {Size={-8.9},Font={*-Caption}},
        {Size={8.91-14.9},Font={*}},
        {Size={14.91-22.9},Font={*-Subhead}},
        {Size={22.91-},Font={*-Display}},
    },
},
ItalicFeatures = {%
    SizeFeatures={%
        {Size={-8.9},Font={*-Italic-Caption}},
        {Size={8.91-14.9},Font={*-Italic}},
        {Size={14.91-22.9},Font={*-Italic-Subhead}},
        {Size={22.91-},Font={*-Italic-Display}},
        },
    },
    BoldFeatures = {%
        SizeFeatures={%
            {Size={-8.9},Font={*-Bold-Caption}},
            {Size={8.91-14.9},Font={*-Bold}},
            {Size={14.91-22.9},Font={*-Bold-Subhead}},
            {Size={22.91-},Font={*-Bold-Display}},
        },
    },
    BoldItalicFeatures = {%
        SizeFeatures={%
            {Size={-8.9},Font={*-Bold-Italic-Caption}},
            {Size={8.91-14.9},Font={*-Bold-Italic}},
            {Size={14.91-22.9},Font={*-Bold-Italic-Subhead}},
            {Size={22.91-},Font={*-Bold-Italic-Display}},
        },
    },
]{Garamond-Premier-Pro}

\begin{document}

\section{Embedding Optical Sizes Test}

\tiny
\begin {itemize}
 \item {\rmfamily \upshape Hello World!}
 \item {\rmfamily \upshape \bfseries Hello World!}
 \item {\rmfamily \itshape Hello World!}
 \item {\rmfamily \itshape \bfseries Hello World!}
 \item {\rmfamily \scshape Hello World!}
\end {itemize}

\scriptsize
\begin {itemize}
 \item {\rmfamily \upshape Hello World!}
 \item {\rmfamily \upshape \bfseries Hello World!}
 \item {\rmfamily \itshape Hello World!}
 \item {\rmfamily \itshape \bfseries Hello World!}
 \item {\rmfamily \scshape Hello World!}
\end {itemize}

\small
\begin {itemize}
 \item {\rmfamily \upshape Hello World!}
 \item {\rmfamily \upshape \bfseries Hello World!}
 \item {\rmfamily \itshape Hello World!}
 \item {\rmfamily \itshape \bfseries Hello World!}
 \item {\rmfamily \scshape Hello World!}
\end {itemize}

\normalsize
\begin {itemize}
 \item {\rmfamily \upshape Hello World!}
 \item {\rmfamily \upshape \bfseries Hello World!}
 \item {\rmfamily \itshape Hello World!}
 \item {\rmfamily \itshape \bfseries Hello World!}
 \item {\rmfamily \scshape Hello World!}
\end {itemize}

\large
\begin {itemize}
 \item {\rmfamily \upshape Hello World!}
 \item {\rmfamily \upshape \bfseries Hello World!}
 \item {\rmfamily \itshape Hello World!}
 \item {\rmfamily \itshape \bfseries Hello World!}
 \item {\rmfamily \scshape Hello World!}
\end {itemize}

\Large
\begin {itemize}
 \item {\rmfamily \upshape Hello World!}
 \item {\rmfamily \upshape \bfseries Hello World!}
 \item {\rmfamily \itshape Hello World!}
 \item {\rmfamily \itshape \bfseries Hello World!}
 \item {\rmfamily \scshape Hello World!}
\end {itemize}

\LARGE
\begin {itemize}
 \item {\rmfamily \upshape Hello World!}
 \item {\rmfamily \upshape \bfseries Hello World!}
 \item {\rmfamily \itshape Hello World!}
 \item {\rmfamily \itshape \bfseries Hello World!}
 \item {\rmfamily \scshape Hello World!}
\end {itemize}

\Huge
\begin {itemize}
 \item {\rmfamily \upshape Hello World!}
 \item {\rmfamily \upshape \bfseries Hello World!}
 \item {\rmfamily \itshape Hello World!}
 \item {\rmfamily \itshape \bfseries Hello World!}
 \item {\rmfamily \scshape Hello World!}
\end {itemize}

\end{document}

I use latexmk to compile the above code:

latexmk -outdir=tmp -xelatex <source.tex>

and

latexmk -outdir=tmp -lualatex <source.tex>

Both commands finish successfully. I opened the two pdf files using adobe reader and examined their properties: Each pdf file contains the embedded optical sizes (caption, regular, subhead, ...). If I open the pdf files using adobe acrobat and highlight a letter or a word, the tool column (edit/insert text) shows the highlighted letters' fontname, where the difference gets obvious: The pdf compiled with XeLaTeX shows the correct fontname, including optical sizes. The pdf compiled with LuaLaTeX shows "regular" for all letters.

The pdf resulting from XeLaTeX seems fine. Is it possible that LuaLaTeX just embeds the optical sizes (e.g. updates the pdf-internal font list), but uses only the font's regular size?

Update

The following screenshots should clarify the differences. The first one shows the result using XeLaTeX:

The following shows the result using LuaLaTex:

Having a look on the properties both pdf files seem to contain the same font set (the list of embedded fonts is identical). But if you have a look on the highlighted "o" Acrobat (Standard Ed.) reports for the XeLaTex-PDF the detailed (correct?) font shape and size ("...-BdItDisp"), where Acrobat (Standard Ed.) reports for the LuaLaTeX-PDF only the basic font ("Garamond Premr Pro") - of course the buttons italic and bold are highlighted, but something seems to be wrong with one of the involved components, my setup, or my usage, ...

Note: I cleaned (removed all files) from the luatex-cache (C:\texlive\2014\texmf-var\luatex-cache), before I produced the above screenshots.