That would seem like a trivial question with a simple answer. But it needs answering given the story that I was told below.
… Walking somewhere along a major street, a man stopped to talk to two folks seated beside materials on dianetics on display. One had an instrument with a dial, and was testing a subject. So he asked what exactly the tester was doing. The detailed response was lost in memory, but it went something like, we’re using our instrument to demonstrate some aspect of human spirituality.
Okay, “test me,” the man said. … If I pinch your arm a bit, you would see the dial move …. And the tester went on to some unacceptable explanation about how that related to what was happening in the spiritual.
His explanation was suspect because, medical equipment like EEG’s (electroencephalographs) and ECG’s (electrocardiographs) could then also be said to be peering into the spiritual. The human body is electric!
After some banter, they agreed to disagree, and he went his way thinking about the people who might have been hoodwinked by their demonstration.
So, what might be a difference between the spiritual and the physical? The spiritual cannot be such that it is subject to the laws of physics.