The easy way to remember it is that the short one is under 2', the long one is over 2'.
I think the difference in length is more like 1.5" than 2".
Canadian-produced engines were all the long block, the thinking at the time being that they could always make a shorter stroke engine out of a long block if they needed to keep the size down.
In other words it was a more flexible unit to be producing if you were only producing the one size at a plant.
For this reason there are small sizes that are very close to sizes for the short block engine.
