display is used to specify how an element is displayed and whether it's visible.
display: none, block or inline;
Position specifies what method we are using to position the object (static, relative, fixed or absolute).
By default, positioning is position:static;, which means an element simply appears in the normal "flow" of the page.
position:relative; is used to adjust an element in relation to it's normal, static position.
position:fixed; keeps an element in the same place on the page, even if the page is scrolled (it's relative to the "viewport").
position: absolute; keeps an element in the same place relative to the nearest previous element that has had it's positioned defined.
Float is most often used in relation to images.
float:right; inside of an image style means the image will float to the right of the text.
clear: left; is used to "clear" a previously used float (see this).
Align is used to align elements either horizontally or vertically. Lots of variations on this one, please see this.