The WPCP250 is a newer version with a lower "ON" level of 1-5/8" utilizing a magnetic float and rated at 31.6GPM, whereas the WAPC250 is a totally different pump configuration, utilizing a "Sensing Technology" switch that activates at about 2-1/2" and pumps about 50GPM. The WPCP250 can handle 23 feet of head, whereas the WAPC250 stops at 17 feet of head.