Meso and achiral does both term means the same?
From the Gold book:

meso-compound:
A term for the achiral member(s) of a set of diastereoisomers which also includes one or more chiral members

Achiral compound:
A compound that can be superimposed on its mirror image.
The difference lies in the presence of the chiral centre. All meso compounds are achiral (due to internal compensation as you have mentioned) but all achiral compunds aren't meso.

Look carefully and you'll be able to spot chiral centres in all the above compounds but you'll also notice that they have a plane of symmetry (internal compensation) which makes them achiral.

Bromocylohexane has a  plane of symmetry which makes it achiral. But it has no chiral centre, that's why it doesn't qualify to be a meso compound.