These two fields often go together, performed by the same team or the same person, but they both have different methods and results.
User experience designer would require more analytical skills, more business knowledge and working with user data, responses and emotions.
User interface designer is an artist combining visuals, movement, interactions, marketing to create a design that fulfils the required functionality, has the needed look and feel and connects with the users.
Here is a great definition by godfathers of UX Dan Normand and Jacob Nielsen:
"User experience encompasses all aspects of the end-user's interaction with the company, its services, and its products. "
These aspects can include a user's behavior, perceptions, feelings, beliefs, desires that accompany his interactions with a company's product or service.
User Interface is the actual tool for interaction between the user and the product/system. This tool should be intuitive, provide ease of use, effectiveness, and learnability.
So what could an usual UX process include?
01_PROJECT STRATEGY
You should listen and understand. Ask client questions till a well defined strategy and a project scope.
Assist the client in defining Value proposition, Business goals, Client Benefits, KPI’s and other complex words.
02_RESEARCH
Carry out a Competitors analysis and business domain review.
Creating personas, user stories, and customer journeys. Validating my research with value surveys, problem interviews or just talking with the right people.
03_STRUCTURE
Time to finalize specifications. Building Information Architecture and the main user flows.
Creating fast-paced design of low-fidelity wireframes and/or paper prototypes. Defining navigation and interaction types.
04_TESTING
Structured usability test, heuristic evaluation and some guerrilla testing with social media and friends.
Talking with people. Listening, empathizing and analyzing!
The UI process
06_DESING_UI
Compose mood boards, find inspiration and build typography, color, layout and interaction rules.
Creating hi-fidelity interactive prototypes. If needed brand rules.
07_ITERATION
Testing with users and Iterating are parts of the UX and the UI process which take part continuously through the whole development.
For someone who is searching his role
Usually UX and UI go together, every UX designer knows the basics of UI design and vice versa. Designing UI can be described as a more specialized part of the UX process. Sometimes in young or small projects UI design would be the whole UX process.
If you are thinking which is better for you, think about what you like. Do you enjoy understanding people's actions, feeling their pains and finding their goals? Analyzing data doesn't scare you so you should think about the UX role. On other hand if you like creating aesthetic products, want to know more about typography, color, movement, layout. Knowledge of where users look and how to convey information, then you should be fine with UI. If you like both - don't worry, most companies would love someone who can do all the work.
Welcome to join the UX / UI design community at its start!
Tell us more about yourself, what you think about UX/UI, what is your role.
Can't promise huge rewards, but I will do my best to reward everybody who creates quality content here.