UI Designer (User Interface Designer)
User interface designers are particular about how the product is laid out. They are in charge of designing each screen or page with which a user interacts ensuring that the UI visually communicates the path that a UX developer has laid out.
UI designers are also typically responsible for creating and/or implementing a cohesive style guide and ensuring that a consistent design language is applied across the product.
Maintaining consistency in visual elements and defining visual behaviour also fall under the purview of a UI designer.
UX Developer (User Experience Developer)
UX developers are primarily concerned with how the product feels. A given digital communication problem has no single right answer. UX developers explore many different approaches to resolving a specific user problem.
The broad responsibility of a UX developer is to ensure that the product logically flows from one step to the next. One way that a UX developer might do this is by conducting in-person user tests to observe behaviour. Another is to apply different technical solutions to achieve similar but more refined outcomes.
The UX developer is also tasked with identifying the best technologies to use for a particular solution, knowing there are always multiple ways to solve each problem, but often online solutions not only require the best solution, but also the most efficient.
They are also tasked with designing the information flow of the solution to maximise the access to the information by the user.
By identifying interaction stumbling blocks, they refine and iterate to create the “best” user experience in the digital space.