The main differentiating factor between an IPL and a laser is the way light source. IPL delivers a broadband light source while laser emit one singular direct light to the hair follicle. Both methods of hair removal introduce heat to the hair follicle that targets melanin.
Both laser hair removal and IPL
hair removal devices provides just enough light to achieve optimal temperature and results without heating up the skin to damaging temperatures in the process. (Blistering is a side effect commonly associated with laser hair removal)
Laser hair removal is more selective and focuses directly at hair follicles, while IPL hair removal devices targets the hair and surrounding area.
In other words, lasers use specific light rays on predefined wavelengths depending on your skin and hair color, while IPLs produce multiple wavelengths in each flash.
Light produced from either device is much rather similar to natural light and is visible to the naked eye as a reddish/orange glow when flashed.