Answer:
A constitution is a body of fundamental principles or established precedents according to which a state or other organization is acknowledged to be governed.
A bit of definition for each of them -
(A Federal Constitution can be defined as one in which powers are shared between the three arms of government namely the Legislative, Executive and judiciary. Hidden categories: Disambiguation pages with short descriptions
In unitary states, the central government may create (or abolish) administrative divisions (sub-national units). ... In federations, the provincial/regional governments share powers with the central government as equal actors through a written constitution, to which the consent of both is required to make amendments.)
So in simpler terms::
In Unitary Constitution the provinces are subordinate to the centre, but in federal constitution , there is a division of powers between the federal and the state governments. ... Both are independent in their own sphere.
Hope this helps! :)