If you use the 1st or 2nd generation AirPods to run, you may find that they do not fit perfectly because they only sell one size. However, the AirPods Pro offers three different silicone ear tips that allow for a custom fit, ensuring that they will not fall out when running.
AirPods are not waterproof. They were never designed to be waterproof. In fact, a well placed drop of water could potentially destroy an AirPod, and though AirPods can withstand the cold, any built-up condensation within the AirPods could cause irreparable damage.
The major differences between the AirPods and the AirPods Pro is that the AirPods Pro offers noise cancellation, a custom fit to your ear, and they are water resistant. There are benefits to each, and which pair you choose depends on what is important to you and and what your budget will allow for.
The best way to clean your AirPods is to gently use a combination of cotton swabs, wooden toothpicks, a soft-bristle toothbrush on all black speakers, and cotton balls dipped in rubbing alcohol for all the shiny white surfaces. You can maintain clean AirPods by simply cleaning your ears on a daily basis.