These different types of lighting create different gradients and colours of light giving an image more meaning and depth. The way the light is enables the image to be more interesting and direct to what you want for your shoot.
New to Lightroom? Need a little help getting the hang of it? I didn't know how to use Lightroom at one point too! Here are 5 Lightroom Tutorials that really helped my photography and my workflow. Check them out! The Educated Shutter