The term Zero Client came about because the line between Thin Clients and PCs has become increasingly difficult to determine – and companies who produce the thinnest clients needed a way to differentiate themselves.
If you can install and run all your applications on a Windows Server (think ‘mainframe’) then to view them remotely you only need a basic CPU, VGA driver, network I/O, keyboard and mouse – a Windows Terminal.
However today you can find “Thin Clients” with local storage, XP operating systems, and a host of local applications. In my opinion this has crossed the line and has become a PC.