Hey, Staro.
I don't know a lot about this subject so I'm going to just throw out what I feel comfortable.
Fire-setting, arson and pyromania.
Fire-setting is just that. People who start fires without a (rational) reason-cooking, warmth, enjoying the fire (fireplace/camp fire). From what I understand fire setting is most common in children. Children are curious. They want to see what happens with a match, grass, wood. No ill intent. Fire setting is a behavior.
However, fire setting can encompass both arson and pyromania. Kinda like the first step to other more nefarious actions.
Arson is a criminal action. The fire is deliberate. The person, most likely men, set a fire for money- to collect insurance or hired by another to collect insurance money or revenge (pay back).
Pyromania is a psychiatric disorder. An impulse control disorder. Pyromaniacs, again usually men, tend to have a history of child abuse/neglect, substance abuse (parents or guardian that will extend to their own life) and poor social interaction/relationships. (You can often see the pyromaniac in the crowd that gathers at a fire. The pyromaniac needs to experience the fire/flames. The heat, sirens, fire trucks , fire fighters, the flames and smoke.) Almost forgot a BIG thing. They get sexual enjoyment and release watching the fire.
(I have also noticed true pyros have a fascination with fire at a young age that extends into adulthood AND wet the bed past the age where it's *normal*)
Firefighters or firefighter-wanna-be's will set fires to *show* how brave and competent they are in that situation.
If anything I posted here makes sense...that would be a surprise. Ha!
(BTW-If I read the article you posted correctly, it piques my interest. The fire was set with people INSIDE the residence at a time most people would know there were people inside and asleep. (Night time) That does scare me. If I had a gun to my head and I had to give an opinion? It was an arsonist. A arsonist who is pizzed with the one or more of the people in the house. )
Or I'm totally wrong. Ha!