Is a game developer and a game designer two different things ?

Depends on the parlance, but yea, they're different.

Game dev more specifically refers to the person doing actual software development work on the game. So, programming.

Game designer can refer to the person who comes up with gameplay, mechanics, story, etc.

Lot of other roles distinct from those two, and the bigger the shop gets, the more granularity you can find in roles. So a huge shop like activision-blizzard might have people whose literal job is to make character models, a different set of people who do character art, etc.

To an industry outsider, the distinction between game design and game programming might seem negligible, but if you plan to make a career out of one or the other, you need to know what’s different. It’s not quite night vs. day, but you could definitely call it concept vs. execution.

While there is little overlap between the two careers, they do go hand in hand. A game can’t be created without both the designer and programmer working closely together from start to finish.

Game designers are responsible for the overall creative vision of the game while programmers have the technological know-how to implement the game designers’ ideas and bring them to life using computer code. That’s only the surface of what these jobs cover within a company.