Both editing and proofreading involve a highly specialized set of skills and a keen eye for detail. They also have the same goal: to improve a piece of writing. However, in general, they focus on different elements of language. Also, editing implies a deeper revision than proofreading, which focuses more on objective errors and mistakes. In a nutshell, proofreading deals with:
Consistency and formatting
Are there any typos? Have all the commas, full stops, semicolons, etc., been placed correctly? Were two different translations used for the same term? Was "there" used instead of "their"? All of that and more are part of a proofreader's work.
I offer both proofreading and editing services of different texts. A piece of writing containing errors affects the overall quality of your text, thus hindering communication with your target audience and even affecting your brand's image; whereas a well-written text that is error-free evokes professionalism and trust, and helps get your brand's message across neatly and effectively.