Jack Pine needles are in bunches of two, which spread apart in a "V". This is one of the main features that distinguish it from Scots Pine.
Here's a closer-up view of Jack Pine needles. If you look carefully at this photo, you can plainly see the spread-apart configuration of the needles.
Immature Jack Pine cones.
Notice how the cones grow directly from the branch, with no stem on the cone. Scots Pine cones have a short stem attaching them to the branch.
Yes, Jack Pine cones do open in fire. These cones were collected from an area that had a fire only a couple of weeks previously.
However, as evidenced by this un-charred cone (on an un-charred tree) still on the tree in an area which had not experienced a forest fire for many many years, the cones do not require fire to open. Good hot weather will do it.
Two pictures showing the overall shape and form of the Jack Pine. They are well-suited to alvar-type places (dry and rocky, with little ground water).