Wisteria sinensis, Wisteria frustescens, and Wisteria brachybotrys twine anticlockwise, and Wisteria floribunda twines clockwise. Hybrids can go either way.
Wisteria floribunda generally have longer racaemes than Wisteria sinensis, and Wisteria Brachybotrys have particularly short ones. With experience it is possible to tell the species from the unopened flower (inflorescence) buds.
In both the American species the stems are more slender looking than the Asian ones and more rare. The flowers are generally more compact.
There are more cultivars of Wisteria floribunda than all the others put together!