I've been flying SK the last few times, so have no recent experience, but officially KL pax ticketed in J use the much nicer Apartment lounge, whereas elites are stuck with the Novia lounge. However, I've been directed to the Apartment lounge quite a few times when traveling in Y. Once I asked, and was told it was because the Novia lounge was too crowded due remodeling or renovations in progress, if I remember correctly.

Johan