Yuru Yuri = yuri = not romance
Hanjuku Joshi = yuri = romance
In addition to making that rather important distinction between serious relationships and not-so-serious relationships, the tag is meant to single out series/stories that focus on romantic developments. Whether that be lots of "I love you, let's be together forever", or the actual illustration of a romance.
With that said, we have quite a group of people who tag things, and many tags have been under some degree of revision at some point. So my words on this hardly hold true 100% of the time.