The following MWE is producing different outputs on XeLaTeX and LuaLateX:
\documentclass{scrartcl}
\usepackage{fontspec}
\setmainfont{FoglihtenNo04-070.otf}
\begin{document}
ffi ew
\end{document}
XeLateX:

LuaLaTeX:

Is this the intended outcome?
The font I chose for testing came from http://www.glukfonts.pl/font.php?l=de&font=FoglihtenNo04.
ss01in LuaTeX I get the same result as you with XeTeX. – Marco Sep 19 '12 at 11:01\fontspec[RawFeature={-ss01}]{FoglihtenNo04-070.otf}. The question is why this is feature set by default. As a user I would not expect this. I don't know enough about OpenType to tell you if the font designer can set particular features as default. But even then, there is still the question why LuaTeX and XeTeX differ. – Marco Sep 19 '12 at 12:38