  Given an Orlicz $N$-function $\varphi$ and a positive decreasing weight $w$,
we present criteria of the diameter two property and of the Radon-Nikod\'ym
property in Orlicz-Lorentz function and sequence spaces $\Lambda_{\varphi,w}$
and $\lambda_{\varphi,w}$. We show that in the spaces $\Lambda_{\varphi,w}$ or
$\lambda_{\varphi,w}$ equipped with the Luxemburg norm, the diameter of any
relatively weakly subset of the unit ball in these spaces is two if and only if
$\varphi$ does not satisfy the appropriate $\Delta_2$ condition, while they
have the Radon-Nikod\'ym property if and only if $\varphi$ satisfies the
appropriate $\Delta_2$ condition.
