If Lion is शेर and Tiger is बाघ Then How शेरा Becomes Tiger ................ courtesy CWG

Dear friends ,
Right from our childhood we have been taught by our learned teachers and our dear parents that 
'' LION is king of forest''which denotes that LION is शेर .And our National animal is ROYAL BENGAL TIGER which denotes बाघ . 
Friends when our commonwealth games are going on ,why this   "SHERA"(शेरा ) has become TIGER .
As every where in English news papers ,CWG website and even in KBC it is being referred as TIGER in English .
Please give your opinion whether it is by default or ''Meaning Is Really Changed''.

Lion ( शेर ) ''The King''

Tiger (बाघ ) ''Our National Animal''