Availing input tax credit for cst payable against cst paid

sir,

Please tell me diffrence between Retail Invoice and Tax Invoice

what is TDS? and procedure of tds deduction and payment .

Can Any one inform me  Why or What is reason or purpose for not aviling CST input same as VAT Input ?

suppose sale is made from maharashtra to west bengal..cst goes to seller state i.e maharashtra...and now if it is allowed as credit for output vat payable in west bengal,  then it will b loss to west bengal goverment..

because it will mean giving credit for taxes which has not come in state treasury..