Firstly there’s no rules or references here, that’s just my take on the topic, there’s no such thing as UI/UX Designer, definitely no UX Developer.

I’ll be trying to explain here a little bit about different roles and what they should be able to do.

UI DESIGNER

While a lot of designers trying to grow into the UX title, good UI expertise is actually also very important and actually shockingly very rare, being a good graphics designer doesn’t mean you understand what it takes to be a good UI Designer.

Bottom line is a UI Designer can transform wireframes to clean, beautiful yet readable, understandable UI’s.

Essential knowledge for UI Designers:

• Basics of designing for pixels
• Layouting, whitespace & Grid systems
• TYPOGRAPHY
• Understanding Colors
• Platforms guidelines at least iOS & Android

INTERACTION DESIGNER

That’s actually the title I see fits more on this designer who is a good UI designer but on top of that he usability and can actually sketch a cool idea of a new feature or interaction.

Unfortunately that’s the kind of designer who often names himself UI/UX Designer as he feels he’s more than a UI Designer but actually never conducted a user research, or lead a design thinking session, or conducted a user testing session.

Essential knowledge for Interaction Designers:

• Essential for UI Design
• Sketching
• Low and high fidelity wireframing
• Usability principles
• Prototyping
• Basic animation for transitions and micro-interactions

UX DESIGNER

Real UX starts initially from the understanding of human psychology, I don’t want to make it look super hard, but at least a basic understanding of user behavior is essential, I mean what’s a UX Designer who’s not good with understanding people ?!

On top of that general knowledge, a UX Designer must’ve spent hours actually observing/interviewing users not just producing imaginary personas, being able to run design thinking sprints, take design decisions based on research and data and being able to prototype and test solutions and take decisions based on it.

Essential knowledge for UX Designer:

• Basics of human psychology
• Basic business goals understanding and interviewing
• Conducting actual user research with real people
• Design Thinking (Defining problems, Ideating solutions)
• Mastering Information Architecture
• Analyzing data and optimizing conversion rates
• User Testing

So here’s a big question, a UX Designer must be an expert in all these fields starting from the UI??

I’d say preferably yes but not necessary, a UX Designer must understand the basics of the other 2 roles but he might leave the job to a more specialized UI Designer for example and focus more on the stuff that only he/she can do.

What if a Designer is really good with the research and design thinking but totally have no clue on the interaction part? then I’d say it’ll be best to name himself a UX Researcher.

Strategists (bonus)

I’d say a senior UX Designer or a Product Designer might need to understand more about business as well, through the last year I’ve read a lot about Creative Strategy and it’s been really awesome when it comes to helping clients achieving their business goals through design, as UX Designers our first question to clients is what’s your business goals, you’ll be thrilled knowing how many times a client doesn’t really have a clear goal or understanding of how this app or feature is going to help his business, that’s why I started reading about Creative Strategy then I felt it’s the missing link between Business and Design that let Design actually solve not just users problems, am I saying every UX Designer must understand strategy, no, not at all, but it’s a huge bonus which can also open the way into growing into other positions like Strategists and Product Manager.