DirectX is a collection of programming interfaces which are often used with games. Such things Direct3D and DirectDraw and DirectSound all work to provide such elements of the game through the collective term 'DirectX'.
DirectX 10 is just one edition, however, FSX only provides a 'preview' mode and is not really the full DX10. DX10 and DX11 only work on Windows Vista/Windows 7 properly. The raw nitty gritty of what there is about it is probably irrelevant, but it's just an updated version and will aim to improve graphics performance and quality.
thanks very much. seeing as i have vista i may as well try to get the full one. How is this done?
Just google for DirectX and it will take you to a Microsoft page where you can get the latest version.
I don't know what you mean by the 'full one', every version is a full version. FSX itself just doesn't use it fully. That's just game specific, not to do with DX10 itself.
Last edited by machineman9 on Thu Nov 25, 2010 3:10 pm, edited 1 time in total.