Translation:A man writes.
They can sometimes be used interchangeably, but 적다 is for writing stuff down that requires no creativity, like taking notes down in class. 저는 노트 적습니다. 쓰다 is used when one needs creativity, like writing song lyrics, or a book, etc. 저는 책이 씁니다.
Yes, think about it as the physical act of writing vs. the concept of writing
Could "Men write" be a valid translation of this? Since -는 can mean in the general sense.