Text - What's the difference between UTF-16 and UCS-2?

UTF stands for Unicode Transformation Format - 16.
UTF-16 is a variable-width 2-byte or 4-byte character encoding for Unicode.
UTF-16 can encode 1,112,064 code points.
The current version of Windows, from Windows 2000 onwards, uses UTF-16.

UCS-2 stands for Unicode Character Set coded in 2 octets.
UCS-2 is a fixed-width 2-byte character encoding for Unicode.
UCS-2 can encode 65,536 code points (0 - 0xFFFF).
Early versions of Windows, from Windows NT 3.1 and Windows 95 onwards, used UCS-2.