It occurred to me the difference between tag and taglink, as described in http://ikiwiki.info/ikiwiki/directive/tag/ is just that the latter enable the option to have a displayed form of the tag different from the tag itself, e.g. a tag `foo` can be displayed as `bar` using 

    \[[!taglink foo|bar]]

while with tag you can only display the tag `foo` as itself

    \[[!tag foo]]

Is that it?