Why isn't my PHP SHA256 hash equivalent to C# SHA256Managed hash

Question

Why aren\'t these the same?

php:

    $hash = hash(\'sha256\', $userData[\'salt\'] . hash(\'sha256\', $password) );

c#

Answer 1

C#

string toHash = "abcdefg"; 
SHA256Managed hash = new SHA256Managed(); 
byte[] signatureData = hash.ComputeHash(new UnicodeEncoding().GetBytes(toHash)); 
string hashResult = System.Convert.ToBase64String(signatureData); 

PHP

print base64_encode(hash("sha256",mb_convert_encoding("abcdefg","UTF-16LE"),true));

Works for me.