On my system, %AppData% leads to ApplicationData which is C:\Users\<USER>\AppData\Roaming
But there is also C:\Users\<USER>\AppData\Local
And for some more confusion D:\Users\<USER>\AppData\LocalLow
string local = Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData);
string roaming = Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData);
My question is, to which of these locations should my application save its data?
Are there guidelines for which of these locations to use? And am I leaving myself open to problems if I choose the wrong location?
The Roaming folder is copied between machines when roaming profiles are enabled (in a domain environment). Use it for application data that you want to share between machines. But don't store large files in there -- IT departments don't like it when you do that, and it increases the time taken for the user to log in and to log out as the files are copied around.
The Local folder is not copied between machines. Use it for application data that's specific to a machine.
The LocalLow folder is used for low-privilege tasks (such as Internet Explorer). You shouldn't need to worry about it.
For files that the user specifically saved, you should put them (by default) in the Documents folder.
According to MSDN the difference is that LocalApplicationData stays on the local machine and does not roam... ApplicationData does roam for example if the user logs onto the domain from a different computer it will be synced...
The LocalLow refers to specific situations likea BHO running in "Protected Mode" of IE...
For a standard application always use ApplicationData. Use LocalApplicationData for things that should NOT roam with the user...
From MSDN - Environment.SpecialFolder Enumeration:
ApplicationData - The directory that serves as a common repository for application-specific data for the current roaming user. A roaming user works on more than one computer on a network. A roaming user's profile is kept on a server on the network and is loaded onto a system when the user logs on.
LocalApplicationData The directory that serves as a common repository for application-specific data that is used by the current, non-roaming user.
In short, use ApplicationData for roaming profiles, and LocalApplicationData for non roaming profiles.
来源：https://stackoverflow.com/questions/9709269/difference-between-specialfolder-localapplicationdata-and-specialfolder-appli