The “Theme” of a WordPress site, such as Green Path, defines a range of possible page layouts, not just one. In order down the page:
(A) All pages will have the same header “banner”. It is normally text but can be a logo, or text superimposed on an image.
(B) All pages will have a “header image” or none of them will. The header image, if used, can be (1) the same for all pages (2) a “slideshow” such this site uses or (3) a random image from a set uploaded for the purpose. I like (3) because I find (2) distracting and (1) dull, but I sometimes chose not to have a header image as such because my logo image fills that role. Like slideshow images, the random images would normally all be relevant to the site but may not always be relevant to the particular page they appear on.
(C) All pages will have the “menu”, the primary navigation tool.
After that, we have choices:
(a) The standard page for posts has a side-bar with “widgets” which may include quick links to other posts, a search box, and (in our case) links to posts on particular topics and (e.g.) “Make a Donation”.
(b) If we want, any particular page can have full-width text and no side-bar.
(c) Or we can have a special “Front Page” layout, but only if we set that page as the “home” page of the site (which we normally don’t want to do because we want our visitors to see our latest news, not an introduction to the organisation).
Any individual pages or posts in either format can have a “featured image” if we want. In some themes (e.g. twenty fourteen) it replaces the header image and is not going to be particularly obvious; in others it appears under the header image and above the text. The featured image has to be chosen by the writer. Of course, the writer can also insert images anywhere within the post or page.
At the bottom of every page we have a “footer” which can have more widgets if we think we need them. At the moment it also has a “back to top of page” link and still includes the automatic “Proudly powered by WordPress” text (I don’t mind giving them that acknowledgement, since they give us the software – it’s all free).
Wrapped around all of this is the “background”, the unused area of the browser’s window. It can be an image (e.g. this site) or a solid colour which contrasts with the background of the page, as here, or matches it, as in the current version of Green Path (green on green).