I've just read about R-Trees:
The key idea of the data structure is to group nearby objects and represent them with their minimum bounding rectangle in the next higher level of the tree; the "R" in R-tree is for rectangle.
This seems to be a Bounding Volume Hierarchy (BVH) with axis-aligned bounding boxes (AABBs):
A bounding volume hierarchy (BVH) is a tree structure on a set of geometric objects. All geometric objects are wrapped in bounding volumes that form the leaf nodes of the tree. These nodes are then grouped as small sets and enclosed within larger bounding volumes. These, in turn, are also grouped and enclosed within other larger bounding volumes in a recursive fashion, eventually resulting in a tree structure with a single bounding volume at the top of the tree.
One of the most commonly used bounding volumes is an axis-aligned minimum bounding box.
Both allow overlapping nodes.
I've learned about BVHs in a Computer Graphics lecture and about R-trees by a professor who is mainly working on databases. So it might be that different communities developed the same datastructure independently.
Is there any difference between R-Trees and BVHs?