I don't think one is more intelligent than the other.
Academically they are equally qualified in their respective fields, as both have doctoral qualifications. Mom is a professor in Romance Languages at one of the top ranked US colleges [universities], Dad is a Supervisory Special Agent within the F.B.I.
I'm sure there are some people out there (I don't mean on here, I just mean 'out there' in general!), who would say my dad is more intelligent because the qualifications he has (his postgrad studies are in Forensic Psychology and Applied Behavioral Analysis) are in a scientific field, whereas my mom's are obviously in languages. In fact I knew someone who once said, "studying a language at university does not require the same 'brain power' as it would studying one of the sciences." 
(Thankfully I met this person at college [university] and we did not stay in contact).
Away from the academics, they both have their strengths. Dad is amazing at remembering random facts; you can be watching a quiz show with him, and the most random question can come up and he'll be shouting out the answer. When you ask how he knows it, he often shrugs his shoulders and says, 'I don't know, I obviously read it/heard it once, and it just stayed locked in my brain'.
Mom has an incredible vocabulary, I have dubbed her The Walking Thesaurus, as if you're struggling to come up with an alternative word for something, not only can she think of one, they're often less obvious ones. Even now I'm living here in England for the time-being, I'll phone her up and say, "Mom - I need an alternative word for xxxxxxxx'.
So yeah, I wouldn't say either one of them is more intelligent, they're both very intelligent but in different ways and different fields.