Consider the following MWE:
\documentclass[varwidth]{standalone}
\usepackage{ifluatex}
\usepackage{ifxetex}
\usepackage{metalogo}
\usepackage{fontspec}
\setmainfont{Bembo}[BoldFont = Bembo Bold]
\newfontface\bembo{Bembo}
\newfontface\bembobold{Bembo Bold}
\newfontface\bemboboldos{Bembo Bold Oldstyle Figures}
\makeatletter
\newcommand{\showfont}{\f@family{}}
\makeatother
\begin{document}
\ifxetex
\XeLaTeX
\fi
\ifluatex
\LuaLaTeX
\fi
\textbf{AVATAR 48} \showfont{}\\
\bembo AVATAR 48 \showfont{}\\
\bembobold AVATAR 48 \showfont{}\\
\bemboboldos AVATAR 48 \showfont{}
\end{document}
And the following output generated with XeLaTeX and LuaLaTeX, respectively:
Note that XeLaTeX does not use kerning when setting in the "Bembo Bold" font in the 2nd line (where the font is selected using \setmainfont and the font face is selected with \textbf), but in the 4th line, where the font is loaded using \newfontface. Also, LuaLaTeX always kerns correctly.
Why is that?


\textbfand using the bold font face loaded directly? – bev Sep 24 '15 at 16:00