\documentclass{article}
%DIF LATEXDIFF DIFFERENCE FILE
%DIF DEL simplefrac-old.tex   Thu Jun 12 00:01:26 2014
%DIF ADD simplefrac-new.tex   Thu Jun 12 00:01:26 2014
%DIF PREAMBLE EXTENSION ADDED BY LATEXDIFF
%DIF UNDERLINE PREAMBLE %DIF PREAMBLE
\RequirePackage[normalem]{ulem} %DIF PREAMBLE
\RequirePackage{color}\definecolor{RED}{rgb}{1,0,0}\definecolor{BLUE}{rgb}{0,0,1} %DIF PREAMBLE
\providecommand{\DIFadd}[1]{{\protect\color{blue}\uwave{#1}}} %DIF PREAMBLE
\providecommand{\DIFdel}[1]{{\protect\color{red}\sout{#1}}}                      %DIF PREAMBLE
%DIF SAFE PREAMBLE %DIF PREAMBLE
\providecommand{\DIFaddbegin}{} %DIF PREAMBLE
\providecommand{\DIFaddend}{} %DIF PREAMBLE
\providecommand{\DIFdelbegin}{} %DIF PREAMBLE
\providecommand{\DIFdelend}{} %DIF PREAMBLE
%DIF FLOATSAFE PREAMBLE %DIF PREAMBLE
\providecommand{\DIFaddFL}[1]{\DIFadd{#1}} %DIF PREAMBLE
\providecommand{\DIFdelFL}[1]{\DIFdel{#1}} %DIF PREAMBLE
\providecommand{\DIFaddbeginFL}{} %DIF PREAMBLE
\providecommand{\DIFaddendFL}{} %DIF PREAMBLE
\providecommand{\DIFdelbeginFL}{} %DIF PREAMBLE
\providecommand{\DIFdelendFL}{} %DIF PREAMBLE
%DIF END PREAMBLE EXTENSION ADDED BY LATEXDIFF

\begin{document}
A simple equation \DIFdelbegin %DIFDELCMD < \verb|\frac{2 a}{3 b}|
%DIFDELCMD < %%%
\DIFdelend \DIFaddbegin \verb|\frac{a}{b}|
\DIFaddend \begin{displaymath}\DIFdelbegin \DIFdel{
\frac{2a}{3b}
}\DIFdelend \DIFaddbegin \DIFadd{
\frac{a}{b}
}\DIFaddend \end{displaymath}
A simple equation with additional space \DIFdelbegin %DIFDELCMD < \verb|\frac{2 a} {3 b}|
%DIFDELCMD < %%%
\DIFdelend \DIFaddbegin \verb|\frac{a} {b}|
\DIFaddend \begin{displaymath}\DIFdelbegin \DIFdel{
\frac{2 a} 
 {3 b}
}\DIFdelend \DIFaddbegin \DIFadd{
\frac{a}
 {b}
}\DIFaddend \end{displaymath}

\section [Section without space]{A \DIFaddbegin \DIFadd{new }\DIFaddend section title without space}

\section [Section with space] {A \DIFaddbegin \DIFadd{new }\DIFaddend section title with space}

\end{document}

