When cutting firewood, I go by the bark. These are two pine species I leave, going for Sugar or Lodgepole instead, with Lodgepole having more BTU's than all the pines, at least in my area of CA. There are times and maybe it is some specimens that happen to be crossed or slight variation, where it is hard to tell what they are, a Ponderosa or Jeffery. I notice in the Lake Tahoe area that the Ponderosa bark is very distinqishable (sp) from Jeffery. Sugar pine splits so much easier than Ponderosa or Jeffery for firewood.