Isomorphic Posets

Two Posets are said to be isomorphic if their ``structures'' are entirely analogous. Formally, Posets $P = (X, \leq)$ and $Q = (X', \leq')$ are isomorphic if there is a Bijection $f$ from $X$ to $X'$ such that $x\leq x'$ precisely when $f(x)\leq' f(x')$.