Maybe you are looking for word-diff
--word-diff[=<mode>
]
Show a word diff, using the <mode>
to
delimit changed words. By default,
words are delimited by whitespace; see
--word-diff-regex below. The <mode>
defaults to plain, and must be one of:
color
Highlight changed words using only
colors. Implies --color.
plain
Show words as [-removed-] and
{added}. Makes no attempts to escape
the delimiters if they appear in the
input, so the output may be ambiguous.
porcelain
Use a special line-based format
intended for script consumption.
Added/removed/unchanged runs are
printed in the usual unified diff
format, starting with a +/-/
character at the beginning of the line
and extending to the end of the line.
Newlines in the input are represented
by a tilde ~ on a line of its own.
none
Disable word diff again.
Note that despite the name of the
first mode, color is used to highlight
the changed parts in all modes if
enabled.
http://git-scm.com/docs/git-diff