Using Limesurvey as a new install in a Mac environment and trying to learn more about using the tool - most support videos and other documents describe a very different looking system - is that a Mac vs PC issue or is that about a new version of the software?

Many parts of the manual are for version 2.06 and before, you probably installed the latest version 2.5.

As this is is a web application that runs in the browser, there should be no major diferences between the design on a Mac or a PC.