For context, I'm puzzling over the larger question of "what, really, is the difference between a rod and a wand?" Obviously one is larger and heavier, so encumbrance might be one consideration.
I don't need a taxonomy of the magical items--"wands generally do this while rods generally do that" is something I could chart up on my own. (I once thought charges were the defining charateristic of wands, but that's not it.)
I'm more interested in "Artifact X destroys wands, but not rods," or "spell Y only works when cast from a rod." Are there elements in the game other than the rods and wands that notice whether something is a rod or a wand?
Put another way: if I'm a GM creating a magic item, aside from encumbrance and flavor text, what are the implications of choosing between a rod and a wand?
For reference, the relevant DMG descriptions from pp.139-140:
A scepter or just a heavy cylinder, a magic rod is typically made of metal, wood, or bone. It's about 2 or 3 feet long, 1 inch thick, and 2 to 5 pounds.
A magic wand is about 15 inches long and crafted of metal, bone, or wood. It is tipped with metal, crystal, stone, or some other material.