Designers and developers are significantly different from each other in that designers use creative tools to record what the imagination invents; developers take those designs and bring them to life via programming languages. A simple analogy being an interior designer working with a construction contractor.
The two roles couldn't be any less similar, yet they're crucial to each other to get the job done. Design is where creativity happens; UX designers, UI designers, visual designers, and the like are who create the magic and give it beauty and useability. Developers are those who bring those designs to life and actually make them work. They might be called front-end developers, website developers, mobile developers or simply - devs.
You'll catch designers using Figma, Adobe, Zeplin (not Led), Sketch, wireframe software Balsamiq and much more. You'll find developers using CSS, HTML, Javascript, C, Swift, Ruby (on Rails), and a boatload more.