The button styles provide a range of visual emphasis depending on the needs of the content.
Feature Button
The "Feature" button is intended for the most important calls-to-action on the page. As such, an effort should be made to limit the number of these on a single page to maintain a clear focus for the content.
Standard Button
Standard buttons are suited for general use such as in sidebars or the main content.
Utility Button
Utility buttons are for controls that don't need to be visually prominent.
Arrow Link
Arrow links are just fancy links for use as a more subtle call to action in sidebars.