Not really the same feature. Typically, scroll-bar clicks will scroll by pages, while the little buttons will scroll by lines. Also: using the little buttons,

Not really the same feature. Typically, scroll-bar clicks will scroll by pages, while the little buttons will scroll by lines. Also: using the little buttons, you can position the cursor once and then click repeatedly for repeated movements, taking you ultimately to the very top or bottom of the page. But when clicking the scroll bar, page movement generally stops as soon as the slider moves underneath your cursor.