No worries, I was rather confused on the topic myself when I first was looking at different tail types.
Crowntails are judged on their three main 'large' fins: caudal (tail), dorsal (back) and anal (bottom). The fin consists of two main parts, the ray and the webbing. The ray is the hard bony support that all of the webbing connects between. Ideally a crowntail's webbing should be of equal reduction (aka how far away it is from the end tip of the rays) all the way around on all fins. But come on, these are bettas from LFS we're dealing with here, I don't expect any of them to show standard, they are here for our personal entertainment. To count as a crowntail, there must be at least a 33% (aka one-third) reduction in webbing in the main fins. Any less, and you've got a combtail. None at all, you're a veil tail or delta, HM, etc - the classification then depends on shape)
Compare Tokyo's Riju to a betta like this for example:
Notice how there is much less webbing between the rays? This is a greater 'reduction'. The betta in the link above has about a 55-60% reduction, and it is consistent throughout all three main fins, so he is a crowntail.
Of course, this is purely when refering to single rays (SRCTs). There are other variations out there in the world of crowntails, some more extravagant than others.
For example: http://www.jotyabetta.com/image/STOCK%20SHOP/ct004.jpg
That is a DRCT, or a Double Ray Crown Tail. Notice how it has two different levels of webbing in it's tail? This is because it's rays split (hence double ray) and there is additional webbing between each split which is at a different level than the webbing between the whole rays.
Eh.... I may just be confusing you further. Would it perhaps be better if I made a board about this on my own later to clear some of these sorts of questions up?