Poseur is dead on. The lights in P4 and P5 are the same. They added the ray tracing capability. In the render settings, when using firefly, you must select cast shadows. I also recommend you uncheck smooth polygons and texture filtering unless you have a specific use for them. lastly, should you use any of the ray traced lighting shaders, you will need to have ray trace checked in render settings to get their full effect -- even if you have no ray traced lights.

thou and I, my friend, can, in the most flunkey world, make, each of us, one non-flunkey, one hero, if we like: that will be two heroes to begin with. (Carlyle)