Raw linseed oil is just that, straight pressed out of flax seeds and strained. It is edible and good to rub on wood. However, it will 'evaporate' (for want of a better word) to about half it's volume if left in the sun or gently brought to a boil. It's boiling piint is about 300 o C though so not something to be undertaken lightly and it will flash into flame if given half a chance too.
Boiled oil is a drying oil, it was the basis for many of the oil paints used in the past, because of this property. However, if boiled oil is left on a rag and that rag is discarded carelessly then the 'drying', which is really a kind of exothermic reaction may very well set the damn thing on fire.
I can't find a clear site giving the gist of this on line but if you have look at this link
http://www.naturalhandyman.com/iip/infxtra/inflin.shtm
at least his information on the use of linseed oil is relevant to the type of woodwork used in bushcraft.
Personally while I quite like the smell I find linseed to be sticky oil and that annoys me. A mix of beeswax and turpentine is a better bet I find.
Cheers,
Toddy