What are the differences between types of soy sauce?
This is a complex question, because there are several different ways to categorize soy sauces: 


COUNTRY OF ORIGIN (Chinese and Japanese are the ones most commonly contrasted --but as you saw in Wikipedia, there are many more), 
COLOR (light, dark, white), 
VISCOSITY (thin, thick, jam), and 
MANUFACTURING PROCESS (This has the most name variation, but there are just two options: fermented or chemical.  Fermented is the "real thing" and also is called naturally brewed, or slow-aged.  Chemical is the quick and, as usual, inferior-tasting alternative that abbreviates a months-long process into several short, chemically-laden days.  Additional names for this unfortunate approach are non-brewed, non-fermented, and artificial. To avoid this type, study the label and avoid anything containing those non-savory corrective ingredients like corn syrup and caramel coloring.)  


To muddy the waters further, add into the mix the fact that flavor is most deeply influenced by the proportion of soybeans to grains -- yet this crucial factor is not typically used directly as a categorization tool.

To focus my research, I tried to find a site that felt as though the writer was speaking directly to you: one that would encourage, and not overwhelm or confuse, as you decide whether to become a soy sauce affectionado.  Specifically, I wanted a resource that clearly addressed FLAVOR PROFILE and USAGE.  Surprisingly, a blogger named Barbara came to rest as my #1 recommendation:  Tigers and Strawberries. I like the simplicity and clarity of her writing style, as well as her experiential platform (complete with honest explanation of her biases).  The endless comments after her post provide additional insights that might be helpful, as well.

Of course, Harold McGee always provides wonderful more scientifically-based, yet still somehow understandable, explanations.  He takes 5 full pages (496-500) in his book On Food and Cooking to discuss soy sauce in all its layered glory.