Lots of Chinese words ending with 家 mean XX master/genius. So Einstein is a 科学家, but some guy working in NASA is only a 科学工作者, while both are scientists in English.
And 家 is a compliment, so you can't literally say "I'm a 科学家" in Chinese even if you're a world-famous genius. Otherwise, you'd sound arrogant or rude. You've got to be careful with this hierarchy in Chinese.
Here's some examples:
scientist
科学家/科学工作者artist
艺术家/艺术工作者writer
作家/作者politician
政治家/领导干部 or 从政的人revolutionary
革命家/革命分子 or 革命者
英语/英文