Keep an open mind. Just because you know of only one type of HTTP server doesn't mean it's the only one. Take a look at all the HTTP servers available in this list via Wikipedia:
There are more than this and often servers just as Jetty, JBOSS, Tomcat, and many others can be dual purposed to serve static content as a HTTP server as well as serve as an application server.
List via wikipedia

EDIT #1
With your edit I think your point is that Apache (the tag) could be associated with both the HTTPD server and the overarching project + the Apache Software Foundation.
I think part of the confusion is that most people associate the apache with the HTTP web server sub-project vs. anything else. For example I think most people would be surprised that Tomcat (another subject) is in fact called Apache Tomcat.
I think part of the confusion stems from Ubuntu (assuming Debian does the same) packages the HTTP server with an executable called apache2
.
What to do?
I think I would be inclined to reorganize the tags so that apache is used as a tag for Apache related items (software, licensing, foundation), while httpd and a synonym tag apache-httpd were used for actual HTTP server related items.
I dislike making apache a synonym for httpd since it can span multiple pieces of software.
httpd
completely (as synonymous withwebserver
, which is less ambiguous) and then give various web server's their own tag. This way, theapache
tag can be also be used to cover the scope of the the project, andwebserver
added for specificity where appropriate. – goldilocks Apr 6 '14 at 13:43