declare @X varchar(50)

set  @X= 'John'

set @X= 'John           '

DECLARE @a VARCHAR(10)
DECLARE @b varchar(10)

SET @a = '1'
SET @b = '1 ' --with trailing blank

SELECT 1
WHERE
    @a = @b
AND @a NOT LIKE @b
AND @b LIKE @a

SELECT 1 WHERE LEN('John ') = LEN('John')

SELECT 1 WHERE DATALENGTH('John ') = DATALENGTH('John')