Yes, we are talking about making identical styles that have different names... names that match your categories.

After you close and re-open Word, the styles should still be available when you open that document, but by default not in other docs. To make a style available to other documents:
Either click the Modify button as you are making the style, or after you make the style, right-click on the style name and choose Modify. In the lower-left of the dialog box is an option "New documents based on this template". When you close Word, you might be prompted to save the changes to the template.

You can select all text that has that style and press Delete, or you can use the Replace tool on the Home tab to remove the text that is of a style... (In the Replace dialog box, with the insertion point in the "find what" box, click the More button then the Format button then click Style and choose your style to delete. Leave the Replace with box blank. Click Replace All.)