Amplitude monopulse tracking vs Phased monopulse tracking

Well as far as mathematics is concerned, I hav the idea and some how know the difference between amplitude monopulse tracking and phased monopulse tracking but actually i have confusion when it comes to the selection of any of twos. So can anyone tell me the difference (performance wise and application wise) between the amplitude and the phased monopulse tracking?

Regards
Kamal