The wikipedia is a good source for stuff like that. Almost any technology you can think of has an article about it, and their articles typically bridge the gap between the too-short (and biased) "white papers" and the too-long/didn't-read detailed documentation.
And equally useful, you can generally find comparison tables between different technologies.
Other than that, there is no such distinction as tomcat and apache-tomcat. Tomcat is one of the 2 main Apache Foundation server products and it provides J2EE functionality, although unlike JBoss, the J2EE support is deliberately left incomplete. JBoss, in fact, embeds a copy of Tomcat within itself rather than re-invent the parts of J2EE that Tomcat provides. The Apache httpd server does not have any J2EE support in it at all, unless you can count the Apache-to-Tomcat connector modules.
Customer surveys are for companies who didn't pay proper attention to begin with.