The term "Java Web apps" includes web-based Java apps like applets and Java Web Start applications. The term "Java Web" encompasses those technologies, along with the technologies that distribute and update the JRE over the web.
Since the applet developers guide is being rewritten, it's location is moving from guides/plugin to guides/jweb/applet_dev.
At some point, the Java Web Start Developers guide should move to a similar location, like guides/jweb/javaws_dev.
At the moment, the previous "plugin" guide remains intact, with a note that says it's deprecated and a pointer to the replacement. But when it goes away, a redirect should be put in its place.
Similarly, the previous "deployment" guide reamins intact, with a note and a pointer. When it goes away, there should be a redirect for it, too.