My opinion is i would use the gray ash in the garden and black charcoal in the orchard. The charcoal is easy to make in an old barrell burned with abscense of oxygen in the brush fire flames.
Biochar = orchard
Ash = garden
Full disclosure as shown below many experts dont think it matters. They are both very high in nutrients. Your trees would get a huge bump of nutrients from ash. I.know peaches and apples love it! I used to get the ash out of the ash trays in my childhood and grow fruit trees from seed using ash. Trash burn barrel ash was used as well. We burned paper and such things.
Biochar is what i used to convert land on my property that wouldnt grow grass into land that now grows heavy bearing fruit trees.