SQLite Forum

NULL values for collation sequence
Collation sequences only apply to text.  NULL is not valid text.  A "null string" (that is, a string that does not contain anything) is actually a string and not NULL.

So it really matters what you mean by NULL.

A "null string" is a string (text) that does not contain anything.  It is a string/text value, and that value is "empty" of content.  Conversely NULL is a specific value that is of the NULL type.  Collating sequences only apply to TEXT values.