By Bonnie C. Baker (WEBENCH® Senior Applications Engineer):
Numerous filter approximations, such as Butterworth, Bessel, and Chebyshev, are available in popular filter software applications; however, it can be time consuming to select the right option for your system. So how do you focus in on what type of filter you need in your circuit? This article defines the differences between Bessel, Butterworth, Chebyshev, Linear Phase, and traditional Gaussian low-pass filters. A typical Butterworth low-pass filter is shown in Figure 1.
How to compare your circuit requirements to active-filter approximations – [Link]