The values in sys.types show max length. VARCHAR(MAX), NVARCHAR(MAX), and VARBINARY(MAX) aren't different data types from VARCHAR(n), NVARCHAR(n), or VARBINARY(n) which is why you don't see the max_length of -1 in sys.types. If you look at the documentation for the sys.tables it tells you the a max_length of -1 indicates that those types are defined as a MAX type.