What is the difference between Photoacoustic and Photothermal?

In photothermal effects, the laser energy is absorbed by the target (like pigment, blood, or water) and converted into heat, which destroys the target gradually while affecting surrounding tissue minimally. In photoacoustic effects, ultra-short laser pulses generate a mechanical shockwave that breaks apart the target without relying on heat, making it ideal for precise pigment or tattoo removal with minimal thermal damage. Essentially, photothermal uses heat, while photoacoustic uses pressure/wave energy.