There are four major rendering kernels in OctaneRender™ : Direct Lighting, Path Tracing, PMC, and Deep Channel Kernel.
They are switchable by changing the type in the Node Type combo box.
In general, “directlighting” is used for drafts (although can be used for final copy), “pathtracing” and “pmc” are used for high quality rendering, and “deep_channel_kernel” is used for analytical output.