GN4 considers "browsing" and "searching" as two different operations.

Browsing

When you select a folder on a navigator, and display it's content in a listing (by clicking the refresh button), it's considered as browsing. The results are displayed normally, but you cannot refine results. If you try to refine the listing by a search dialog box (Search menu), you'll find out that the folder is not automatically initialized to what's displayed in the listing. Moreover, if you try to select Search again (in the Search menu), it won't work.

Searching

When you enter criteria on a search pane and display the retrieved results by clicking the Search button, it's considered as searching. The results are displayed normally, and if you can refine the results by a search dialog box (Search menu).

See also

Difference between Search and Search again