Cells that carry signals to or away from our brain and make connections within the brain are called neurons. Our sense organs contain neurons that can be activated in different ways. For example, in our nose we have olfactory receptor neurons that detect various chemicals and send signals to our brain that we then process as various odors. In our eyes we have photoreceptor cells that detect photons of light and begin the cascade of sending the signal to our brain. In our ears we have hair cells that move with vibrations and send signals to our brain. Although the signals start in different ways, they are all sent through neurons that use action potentials.
An action potential is an all-or-nothing event that results in an electrical signal being sent through a neuron. In order to perceive intensity (such as a loud sound vs. a quiet sound), action potentials are sent with greater or lesser frequency. For example, a loud sound will result in more action potentials being sent through the neurons to the brain than quiet sounds.
So, neurons in our sense organs are all sending signals to the brain in the form of action potentials, but they begin the signals in different ways.