I am preparing to graft for this first time next spring. I am
researching various articles on the subject. One point which I would
greatly like clarification is how to distinguish "last season's growth"
from older growth.

A little background:

I have been admiring an old crab apple tree in a nearby park for some
time. The apples make great jelly. I have a young (2-3 years?) crab
apple tree in my yard purchased this year. I want to graft scions from
the old tree onto the new one.

Thanks

Robert