Unhulled sesame seeds can be either light brown (golden) or black. Other than their color, are there other differences are their between these two varieties? Why might you choose one type over the other (again, I only care about reasons that aren't related to color or aesthetics of a dish).
Dark sesame seeds are more common in Indian cooking. I personally think that they have a more intense taste. They are also smaller, for what little difference that makes. I wouldn't rush to use them to make tahini, because the color would be surprising and I suspect that the flavor would be a bit bitter.
Black sesame seeds do impart a stronger taste than regular sesame seeds, especially when lightly toasted in a dry pan. They are great ground and added to rich beefy soups or broths.
White sesame on the other hand, has a slightly lighter taste. Toasted white sesame seeds go great mixed with tuna mayo and red onion. They also go very well with chicken and some fish dishes.
Overall, white sesame goes well with lighter coloured and flavoured dishes. Black sesame goes well with darker and stronger flavoured dishes. At least that's what I do. Of course, you can try them with whatever dish you like. These are just some personal preferences.
Oh and black sesame oil, for some strange reason, does not impart as strong a taste as white sesame oil. Asians add black sesame oil to noodles to impart a wonderful taste.