It is a design goal of HtX to be as compatable as possible with LaTeX. Note that, as with LaTeX, line breaks are usually meaningless (except in verbatim environments). Double-line breaks produce the HTML <p> tag.
Now, if you look at the HtX source, you find that you can use < and > without worry .. HtX takes care of turning them into entities.
Other obvious correspondences are italics and bold-face commands (using \bf and \it; see the HtX source.