Hi,
MPC5775E contains 2 ADC modules (EQADC_A and EQADC_B) and each module has 2 converter cores: ADC0 and ADC1. That's why this MCU has 4 ADC quantities.
MPC5775B has just single ADC module EQADC_A, i.e 2 ADC quantities as stated in feature table.
Each ADC module has 6 CFIFOs and 6 RFIFOs and therefore you see so many interrupts vectors, to cover each FIFOx.
BR, Petr