The true needle leaf doesn't grow a wider leaf than about 5mm wide, but can easily grow > 30cm tall. It also likes to fork the leaf tips as a trident does.
Taiwan grows about 10mm wide leaves and can grow > 50cm tall. Yet not seen it fork its leaves.
In the picture below taken during a water change, you see the true needle leaf a few years old and as wide as its leaves will get, above it the Lilaeopsis brasilliensis to compare size.
I now there exists an article dedicated to alleged Java fern needle varieties.. I see if i can find it back.. It has a lot of pictures and explains all the difference to determine what is what. It's German origin article, but I don't remember in what language is. I believe it was English. I'll find it back...
I bookmarked it. but forgot on which computer.
Edit - Got it... Unfortunately, it's in German. But google translate might do good enough, but google translate might do it...
http://aquascaping.flowgrow.de/aqua...-needle-mini-oder-taiwan-javafarn-was-ist-was