Commerce Reference Store makes a distinction between category pages and browse pages. A category page is triggered when a query is composed of a single dimension value from the Category dimension, for example:
Category=Women
Browse pages are triggered whenever a shopper enters a search term or selects a refinement during the browse experience (in other words, for any condition except the category page condition). For example:
[search terms]
[search terms] + Category=Women
[search terms] + Color=Red
Category = Women + Color=Red