Quick start

\documentclass{article}
\usepackage[review]{texchanges}

\begin{document}
This \txreplace{draft}{revised} sentence contains a replacement.
This paragraph has \txadd{new text} and \txremove{old text}.
\end{document}

Compile in review mode to show markup. Change the option to final to render proposed text or original to render the initial document.

The replacement command always uses \txreplace{old}{new} in the native API.