Volume 1 seems a good overview of different things(e.g., carburetor, distributor, ammeter, brakes, etc.) and goes into the brakes a water pump a bit more than the others. Volume 2 has the steering column information and goes into a bit more depth with that and a few others(generator, transmission).
I think at the time it made sense to get both pricewise; oddly enough, volume 2 ended up being better for what I needed, which was the steering and transmission, however I'm glad I have volume 1 just in case. I'm planning on getting the red Les Andrews book; keep hearing good things.