The Bullets field is typically used to hold a description summary of the product (as a bulleted list or a paragraph), which appears by default on the product details page up near the product photo and price, above/outside the tabs area.
The Long Description 1-5 fields are typically used as the source of content for the tabs on the product details page (or can be used outside of the tabs via merge codes). Only the tabs that you have content in for a particular product will be visible on that product's details page.
By default, all tabs in use will be named "Details". These tabs can be renamed to relevant topics for your product (such as "Features", "Specifications", "Package Contents", etc), either on the level of individual products ('Settings' tab under Descriptions), or across the whole store in the Product Details page configuration in the Theme Designer.