MSP430F67791AIPZ  is a direct SUBSTITUBE for MSP430F67691AIPZ

MSP430F67791AIPZ has 7 ADC while MSP430F67691AIPZ has 6 ADC, the rest of the technical information is same, so MSP430F67791AIPZ is a direct substitube for MSP430F67691AIPZ