The "images" button has always been there for as long as I can remember. The "images" button also appears in Bing and Yahoo and probably other search providers.
The mundane 'images' button is unimportant except for some eye candy but the different ways to be specific about searches is the point. This page leads to information about customizing the searches. One of the functions is to limit searches to a specific web site. Scrolling down to the bottom of the linked page there are some links to instructions about different ways to make the most use of it.
https://encrypted.google.com/advanced_search?q=eur7vcty&hl=en