There a couple of misconceptions here. First, a revolver is just a pistol with a feeding mechanism in the form of the cylinder rather than an magazine. Second is the Knockdown Power Myth. If I am remembering correctly, .38 is only a bit bigger than a 9mm round. It still lacks the mass and/or velocity to start getting into the nastier pressure cavities, both primary and secondary, seen with wounding caused by higher powered/faster traveling rifle rounds (which can be the same size or smaller than pistol loads, such as .223/5.56 rounds used in the AR-15) or the devastation that can be caused by more weighty shotgun loads (massive projectile in the case of a slug, or through quantity of decently massed projectiles as per buckshot) which can cause instant incapacitation. From what I have read (and I am not an expert), handguns are largely similar in terms of terminal ballistics until you are getting into the hand cannon ranges (.454 Casul or .500 Magnum). This is a very extensive topic. A couple of good starting points can be found here though:

Ballistics Data Repository https://www.ballisticstudies.com/Knowledgebase.html?selected=wound%20research

FBI Ballistics Data http://www.gunlink.info/downloads/FBITermBal.pdf

Edit: One more for Jesus... (Concerning the Myth of "Knockdown Power") http://theshastalaker.com/Jefferson_State_TRUTH_ABOUT_HANDGUN_KNOCKDOWN_POWER.htm