What is the difference between Bind and Lexical parameters?

BIND VARIABLE:

• are used to replace a single value in sql, pl/sql
• Bind variable may be used to replace expressions in select, where, group, order by, having, connect by, start with cause of queries.
• Bind reference may not be referenced in FROM clause (or) in place of
  reserved words or clauses.

LEXICAL REFERENCE:

• You can use lexical reference to replace the clauses appearing AFTER select,
   from, group by, having, connect by, start with.
• You can’t make lexical reference in a pl/sql statement.