Single or double backslash in file/directory names?

[Bec_a_Fuel]

While playing with USBHost, I have noticed that some names use only single backslash while others are using double backslash :

See the “Directory” and “DirectoryName” here.

Are there any specific reasons behind this ?

Same for DriveInfo, btw.

[Dat_Tran]

isn’t it a different between {…} and “…” ?

[Bec_a_Fuel]

Slight difference

Now I understand. Thank you.