NOT EXISTS vs LEFT JOIN

SELECT st.*
	FROM sys.tables st
WHERE NOT EXISTS ( SELECT 1
		FROM sys.objects so
	WHERE so.object_id = st.object_id AND so.name = 'blah')
GO

SELECT st.*
	FROM  sys.tables  st
		LEFT JOIN sys.objects so ON so.object_id = st.object_id AND so.name = 'blah'
WHERE so.object_id IS NULL