SQL Server 2016

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CREATE TABLE dbo.Strings (
	Column_1 NVARCHAR(MAX)
	,Column_2 NVARCHAR(MAX)
	,
	)

INSERT INTO dbo.Strings
VALUES
('Swetha working', 'Swetha is working in Chennai'),
('Raju 10th', 'Raju is studying 10th std'),
('ranjith', 'Rantith played yesterday'),
('how to play', 'how to play Cricket'),
('My name is', 'my name is john')

/* FOR SQL Version 2017+
SELECT b.Column_1
	,b.Column_2
	,STRING_AGG(b.VALUE, ' ')
FROM (
	SELECT *
	FROM dbo.Strings
	CROSS APPLY (
		SELECT VALUE
		FROM STRING_SPLIT(column_2, ' ')
		WHERE VALUE NOT IN (
				SELECT VALUE
				FROM STRING_SPLIT(column_1, ' ')
				)
		) a
	) b
GROUP BY b.Column_1
	,b.Column_2
	*/
	
	
;WITH split_words
AS (
	SELECT *
	FROM dbo.Strings
	CROSS APPLY (
		SELECT VALUE
		FROM STRING_SPLIT(column_2, ' ')
		WHERE VALUE NOT IN (
				SELECT VALUE
				FROM STRING_SPLIT(column_1, ' ')
				)
		) a
	)
SELECT *
	,(
		SELECT sw.VALUE + ' ' [text()]
		FROM split_words sw
		WHERE sw.Column_1 = s.Column_1
			AND sw.Column_2 = s.Column_2
		FOR XML PATH('')
			,TYPE
		).value('.', 'NVARCHAR(MAX)') [difference]
FROM dbo.Strings s

Column_1	Column_2	difference
Swetha working	Swetha is working in Chennai	is in Chennai
Raju 10th	Raju is studying 10th std	is studying std
ranjith	Rantith played yesterday	Rantith played yesterday
how to play	how to play Cricket	Cricket
My name is	my name is john	john