If you're looking for smartphone deals, these $100 Sprint phones are a good place to look. The Evo Design 4G is actually a new device, despite the fact that it bucks the dual core CPU build that is so popular now among the mid an high-end smartphone devices. Nexus S has been out for over a year, so it's less surprising that it has the single core build. Both devices run Android, obviously, and have four inch screens. The Design 4G has better screen resolution though, 960 x 540 compared to the Nexus S at 800 x 480.
Furthermore, they both have five megapixel cameras and similar sized batteries. So they have similar specs and are the same price. So which one should you choose. It depends on what you want. The Nexus S is pre cursor to the Galaxy Nexus and is a Google branded phone. It gives the pure Google experience with less of the carrier added apps and customizations. It has a slightly curved design for increased comfort and even has a near field communications chip that supports tap-to-pay functionality.
Evo Design 4G comes with HTC's Sense UI, a custom skin that some people like and others hate.
These two devices are a great metaphor for what many people have to choose from when it comes to smartphones. Most can't afford the $200 and $300 price of the best devices out there and so they have to try and figure out what exactly they are getting for around $100. These two phones are quite similar and the differences they do have are hard to discern because they are not the flashy features that get advertised with the big boys. So if you are considering these because you are upgrading or if you are buying your first smartphone will help determine which to pick. If you've had an HTC device before and you like the Sense UI, try the Design 4G. If you are switching from another Android device, say an LG or Motorola, you might prefer the pure Android goodness of the Nexus S. This phone showdown is a draw because the phones are so similar, but tell us in the comments if you've had either one and what you think of them.