Dimensions: Both sconces are 16″ high, and roughly the same width.
Light Bulb: The Inspo uses a standard E26 bulb base, and The Dupe, a candelabra E12.
Materials: The Inspo weighs 11 pounds, and The Dupe weighs 2, so you can imagine there is a significant difference in the build quality, also evidenced by the price! Both sconces come in a range of finishes: brass (as shown), bronze, and nickel.
Bonus: Both of these sconces are wet rated, meaning they can be installed in a bathroom or outside and survive.