There is an excellent course here on CGCookie that explains how the Mapping Node works:
https://cgcookie.com/course/working-with-custom-transform-nodes-in-cycles
Personally I would always use two Mapping Nodes in the above case, because it is more intuitive,I think and also, changing the setting from Point to Texture means Blender makes a matrix multiplication under the hood for each point in 3d space, before performing the mapping transforms. Now the Rotation is also done via a matrix multiplication, so with one Mapping node you have two matrix multiplications (which are quite ‘cheap’ by the way ), with two Mapping nodes (left at Point) you only have one matrix multiplication. Surprise!
Point is a bit of a vague term here, but what it means is that every point in 3D space is transformed.
Changing the Location is just adding the same vector (the one you fill in in the Location field) to each point in 3D. (The ‘name’ of each point, meaning the coordinates, depends on the Texture Coordinates you are using.)
Changing the Rotation is performing a matrix multiplication on each point and changing the Scale is term by term multiplication of the vector and each point.
