monostatic radar vs bistatic radar

"What is the difference between monostatic radar and bistatic radar?" This is the question asked by the interviewer in Poon's job interview at O many many years ago.

monostatic radar—The most common radar system configuration, with the radar receiver at the same location as the radar transmitter. In such a system, surfaces of constant range are spheres centered at the radar site, and only the radial component of target velocity causes a Doppler frequency shift.

bistatic radar—A radar system configuration with the receiver located at a site different from the transmitter. In such a system, surfaces of constant range are ellipsoids with the transmitter and receiver sites as foci, and the component of target velocity that induces a Doppler frequency shift is the component normal to the ellipsoids.

(Extracted from Glossary of Meteorology of the American Meteorological Society)