Hi Supun,
there are differences in the stackup edior that you open in PCB and HL Linesim and HL Boardsim.
This differences are dependent on the version that you have of the tools.
For this discussion I will assume that you have the latest version of PCB (EEVX1.1 or EEVX1) and the latest version of HL (v9.2 or v9.2upd1).
If you have older versions of the tools the situation is even worse.
IF you define a stackup in PCB the editor appears to be similar than the HL editor (This was the great step forward in VX.1) The difference is that in this stackup you are only allowed to have one prepreg between copper layer and the outer copper layer can not have a metalization layer.
If you move your design to HY by export it depends on the format you choose. If you choose hyp format then your stackup will revert to a defaul stackup with part of the info taken from the pcb. If you use cce format then most of the data is correctly transferred to HL.
In HL it is very important that for the prelayout simulation you use the "free form schematic" that generates ffs files. The advantage is that if you use the integrated stackup editor you can export or import a stk format to reuse the stackup. If you use the old tln format you loose this capacity. In both cases the stackup editor seem the same, and it allows to put more data than in PCB, here you can add more prepregs between copper and add metalization for the real simulation.
If you import the board (in cce or hyp) you can use the stk format to import the exact stackup from prelayout into boardsim and quickly start postlayout simulation. If you used the old prelayout format and you could not save the stackup, then in postlayout you have to reenter the stackup.
As of today there is no way to import a stackup stk into layout. You will always have to edit the stackup in PCB first and once in HL either correct the stackup or import/export to stk for later use or for postlayout simulation.
Hope this explanation helps.
Matija