There is a story that old miners in the Sierra would use the sap from Ponderosa to make turpentine which they used for lighting(?) I suppose. When they moved higher into the mountains a few of them got a nasty surprise when they couldn't tell the difference between the Ponderosa and the Jefferey pines. Turpentine has to be distilled apparently and the sap of a Jefferey contains heptane which is highly flammable - the result of their efforts was that they got an exploded still when they tried to make turpentine. These guys may not have been the smartest nuts, but they were smart enough to be able to make turpentine so they had some skills.
My point is that it is very hard to tell the difference between a Jefferey Pine and a Ponderosa - especially given that there are sub-varieties of each (if not named there is still variation as with any species.) I think that the best way to tell is to smell them - no smell is Ponderosa, vanilla-pineapple, or something like that - Jefferey. I own four "Ponderosa", one of them smells quite distinctly, almost all the time, the others have no smell, the buds and needles all look nearly identical. I've never seen a cone on a collected Ponderosa, but that would be one way to tell - Ponderosa I believe have much larger cones - or is it the other way around...? I'd have to go check my book to be sure.