Personally never heard of UI Developer exactly.
Developers are developers and designers are designers. Also personally I don't agree with that amount of specialization that's happening today, everyone should know a portion of most things to be able to communicate between different fields. And this is why I like most about nowadays, the areas are being more and more mixed up and "forced" to be in contact with each other.
UX Designers could know something about programming for prototyping, for starters, and mind that I used the word "could". Designers are not forced to know that, their basic knowledge ends in its own area, but that also makes you a "Basic Designer" that don't communicate well with any other area. I like to encourage designers to learn programming, since we build things to be made, not to be observed, and that knowledge helps you a ton, to be able to design feasible things, just taking care to not limit yourself too much.
Developers are focused on the functionality and applicability of those designs, they need clear instructions to build what was designed, and most cases today, the knowledge of UX and UI gives a great deal of information for those instructions to be even clearer, and also, they become one more looking for the product with a "UX lens", as well as a designer who knows how to program looks to a product with a "Dev lens".
I say this because I'm one of those, I study and graduate myself as a Designer, specifically a UX Designer, but work in a company as a Developer. Each step of my work here can be clearly separated, when I'm "being" a designer and a developer.
It's not the best position, as the only good thing you have is that the communication between Designer and Developer is seamless (since I'm the same person) but comes with the downside that I can't fully commit with any of those areas.
In the end, if you need a designer, focus on finding a UX Designer, but put programming as a "plus", there are great designers out there that doesn't say they know how to "code" but have a great deal of logical thought and could easily be inserted in the developers pipe to communicate with them.