Editing has always been a fundamental component of writing as well as a separate function, but as self-publishing, online and in print, has become ubiquitous, it’s important for writers to realize the distinction. A discussion of the differences may also help you confirm where your strength lies.
It is common for people to double up as editors and writers; I am among the many who do it. But most people feel more adept in one role or the other. I’ve written news and feature articles and opinion pieces and other content for newspapers and other media, as well as these posts — I’ll have written nearly a thousand of them by the end of this year — but although I enjoy writing, I actually prefer editing.