What is the difference between primitive Hexagonal unit cell and Hexagonal closed packing HCP
With the help of these Bravais lattice can HCP be formed?


Yes. One choice of unit cell for HCP is a primitive hexagonal cell with two atoms per unit cell. If you place the first atom on the origin, the second will be at (1/3 2/3 1/2). Here is a 3D view of the situation and some more information: http://lampx.tugraz.at/~hadley/ss1/crystalstructure/structures/hcp/hcp.php


  Should HCP also be placed among 14 Bravais lattice?


No, because it is already in there, just hiding a bit. If you look further into it, the space group is #194, P$6_3$/mmc, see http://img.chem.ucl.ac.uk/sgp/large/194az1.htm