How do identify the order received is decree or not

Please read Section 2(2) of CPC, 1908. It will answer your doubts.

if the order says, suit is decreed as prayed for in the last page, and the first page of the order bears the heading O.S No. xxxx and not IA no. xxxx in OS no. xxxx, then its not a final decree and only an order obtained in an interim order...

even a final decision of a case will have a decree and judgement. 

A decree just states the result of the case ,whether the relief sought is granted or not.

Wheres a judgment gives the basis on which the relief is granted or not.

Since you say the copy bears the word ORDER, it is most probably an interim order and not final decree in a proceeding ./..\