Farmer's hands are short, stubby strong hands, usually calloused and warm.
Preacher's hands are long, thin, hands. They are more often cold, and sometimes have a pale white pallor.
I don't know how much truth there are in colloquialisms, but they seem to make sense.
No offense to farmers, preachers, or anyone else.
No animals were harmed forming this particular opinion.
As always, YMMV.