The signal is the same; it’s the starting and ending points that differ.

The touch activates local sensory neurons, which generate an action potential. This signal is transferred to the somatosensory cortex of the brain (soma = body, literally the body sensing part of the brain). There is point-for-point correspondence of each area of the body to specific points on the somatosensory cortex. This is called somatotopy, and is how the brain knows which part of the body is being touched.

Read about it here.