A character (or a text) style is a collection of character formatting attributes that can be applied to the highlighted text in a single step.

A paragraph style includes both character and paragraph formatting attributes, and can be applied to a paragraph or range of paragraphs. Paragraph styles and character styles are found on separate boxes on the Formatting toolbar of the Articles and Pages main tab, from where they can be applied.

A tag can be either a collection of character formatting attributes or a collection of character and paragraph formatting attributes - the main difference between tags and styles is that the tags are created as "hidden styles", so they will not appear in the styles palette, but you can apply them by typing tag in the source pane or by shortcut keys (if any).

When you change the formatting of a style or a tag, all text to which the style or a tag has been applied is updated with the new formatting characteristics.