Answer:
Aloe is a genus of approx. three hundred plants, a few of which are traditionally used medicinally. Aloe vera is a species of the genus Aloe and is probably the widest known of the Aloes. Generally speaking, when a product contains "aloe" it is a reference to the juice or an extract from A. vera, although sometimes other plants may be used such as A. Arborenscens.
The most potent of the medicinal aloes is A. Barbadensis Miller. Aloe Vera is the common name of this plant.