When the relevant experts, Anthropologists, say that the concept of race is a social construct with no basis in biological fact they aren't just bowing to some ivory tower overlord of political correctness. We would do well to consider their expertise as a starting point in any such inquiry.

Start anywhere on a map of the Eastern Hemisphere and trace what the people look like in any geographic area relative to the regions beside them and then consider why the term "race" has any meaning. sami, swede, finn, rus, tatar, khazak, turk, kurd, arab, berber, ethiopian, tutu. Or Han, mongol, uiger, kyrgir, uzbek, khazak, pashtun, persian, punjabi, hindi, bangali, burmese, thai, javanese, dayak. Where exactly do you parse the line of Caucasian, Negroid, Mongoloid? And why?

Historically, in the cultures from which our culture was derived, skin color, and later eyelid morphology, has been used to define three races (conveniently ignoring the pacific ocean and western hemisphere), for no reason other than the biases of the people in those cultures. If you actually look at facial structure (and why not, no less arbitrary) you'll find the people of the horn of africa have more in common with central european populations in terms of nose and lip shape than they do with more inland African populations. It is our bias to see skin color as more relevant than nose morphology that causes us to group Ethiopians with Hottentots and Biafrans as a single race. We could just as easily group them with Arabs, Berbers, and Kurds. An albino from the Indian subcontinent could claim without fear of contradiction to be an albino of just about any heritage in south asia or europe. Burmese and Japanese have vastly different average skin color but we arbitrarily group them together because of eyelid morphology.

So your question becomes "If different people..." to which the answer is: Of course.

The question you think you are asking, I think, is best rendered "Are those morphological features our modern society arbitrarily associates with membership in three arbitrary sets of humanity also associated with specific brain variations?" Which is exactly as arbitrary a question as "Is foot length/ back hair/ bilateral kidney symmetry associated with specific brain variations."