'Bioflavonoids' are a class of nutrients found in plants that share one of three similar structural backbones; a simple disambiguation of their structures and subcategories can be found here.
They are broken down into Flavones, Isoflavonoids, and Neoflavonoids initially. Each of these categories can be broken down further, but this page encompasses them all.
There are some properties that these compounds possess that is common to their structure, and some differences exist between compounds because of their structure. For example, due to their structure Isoflavonoids are more potent at interacting with estrogen when compared to Flavones.