Blogger Custom domains are more like a Vanity URL for your BlogSpot blog. It will allow you to create a better and easy to remember URL. (for example : from yourblog1234.blogspot.com to yourblog.com)
Blogger allows you to seamlessly integrate with any domain name. To start off you have to make your GoDaddy domain to point to Google's servers. This simple tutorial will guide you step by step with screenshots and instructions to make it easier for you.