Many companies and even marketing companies within these companies do not realise there is a difference between marketing and branding. A brand is not just a logo, name or colour ways it is a lot more. The idea of branding is basically offering your customers a promise and delivering on that promise. Defining your brand will help you in the future as you will already have a business based around an idea / promise / look and feel that you have already established and so therefore it is easier to grow it knowing what your end goals are.
Marketing is basically promoting your message / brand and promises to your customer base. This can be done in a number of ways such as Social Media Marketing, Pay per Click Marketing, other forms of Online Marketing and Offline marketing.
So to sum up a brand is basically your whole business – your logo, corporate look and feel, promises, ideas and marketing is a way to circulate these messages and your company brand out to the wider audience.