Concatenation against NULL expressions + SQL Server 2012

--Using CONCAT function 
SELECT CONCAT(GETDATE(),2,NULL) AS ConcatAgainstNULL

output
ConcatAgainstNULL  
Mar 20 2015  3:59PM2

--Using Plus Operator 
SELECT GETDATE()+2+NULL AS PlusAgainstNULL

PlusAgainstNULL  
NULL

CONCAT treats/converts the NULL operand/expression as EMPTY String whereas the PPLUS Operator treats NULL as unknown value. so any operation agaisnt NULL results NULL in case of Plus operator