The latter are active components and can be directly researched
The former are plants that are pretty much proprietary blends of said active components, and the effects of the herbs are usually through these active components (and benefits could potentially be gained through just said component).
Hopefully this change will increase readability of the site. Hit me up on Twitter @Silverhydra if there are any questions regarding this change or other changes you want to see to Examine (or just drop an e-mail to the editors).
Also note that some plants have not been highly examined. The items listed in those bulleted lists may not (probably will not) be comprehensive.