Designer vs Developer
Designer’s job:
A web designer uses graphics and graphic design software (think Adobe Photoshop, Illustrator and InDesign) to create a look for the web. This design is then married with coding to bring it to life online.
The designer may not always be the person writing the code and in some cases can work independently of the team who will take a website design live.
Much of a designer’s job is creative and uses both intuition and imagination, often characteristics of people who are considered right-brained. People in this field may continue their educations in a variety of fields but are most commonly drawn to graphic design and the arts. Designers collect work portfolios to showcase their projects for potential employers.

Developer’s job:
A web developer builds the backbone of websites, typically from the ground up, and knows languages specific to the web. HTML, Javascript, JQuery and CSS are among the tools in their kit. Developers, historically, don’t focus on making something look visually appealing but create websites with clean code and that are technically sound.
Web developers are often thought of as left-brained workers. Skills from technical ability and thinking to logic are an essential part of their repertoires. Web developers may have degrees in a variety of fields such as computer science or programming. Most employers will require a portfolio during the hiring process.
The best developers are often detail-oriented and are keen on specifics.
Designers feel more like a customer and less like a designer when they hand things off to developers.
Two jobs, One goal

At the end of the day, both web designers and web developers are working toward a singular goal – to create a website or app that entices and attracts users.
To do this, both the design and development must be sound. A site needs to look good and function properly. The colors and imagery need to reflect the brand and the interface needs to encourage visitors to take a desired action.
The defined lines between designers and developers are becoming more blurred as more designers are learning to code and more developers are paying close attention to design theory. (Just one of the reasons why design and development articles and tutorials are so popular.) We are all beginning to see that the future of the field includes the title web designer/developer.
3 design principles: 1.Firmatis. 2.Utilitas. 3.Venustatis.
Users don not like changing so the designer should set up a stable system. Designers also need to think about the appearance of an app or a website. They can use layout, color, shape, gif, picture to create feeling. When you use layout, make sure users can read clearly and easily understand.
UX research: Before you promote a product you need to know users’ needs and their information. Then you improve your product and after-sell service as the changing of environment and competition.