One of the benefits of having a professional design created is that you’re able to submit the website to galleries around the web and have it showcased to audiences that you would have otherwise never been in front of. This brings in added traffic, potential clients and also adds to your authority by being talked about across the web and showcased as a professional website.
The difference between Designing and Development is that designing is everything that the user sees when they go to a site. The development in general terms is everything that goes on it the backend. Usually having a scripting language and a database.