Detecting differences in the type of whiskey used to soak oak

I'll go out on a limb and say that there's not a prayer you could tell the difference between 2 similar types of whiskey, like Jimb Beam vs Jack Daniels, or 12 vs 18 year anything. There's just too little actual whiskey in the 5 gal of beer.

Now you might be able to distinguish say, and American Sour mash bourbon from a peaty Scotch.

I don't think the age of the Scotch would make much difference, but some Scotches have more of a peaty, smokey smell to them than others, and that flavor should carry over to the beer. But if that's what you're going for, you could just use smoked peat as part of the grist (I'm not a fan of this, but you might like it as it imparts a bacon-like flavor).

As far as if you could tell the difference between different brands, I think it would depend on how much whiskey the person drinks. Someone who drinks it frequently and has a preference for one brand would likely be able to tell the difference, but I think the average drinker wouldn't notice.

And bourbon aging definitely has a different flavor than Scotch aging. I've had many bourbon oaked brews, but didn't try any Scotch barrel aged brews until Paradox from BrewDog. The flavor is distinctly Scotch, and very interesting (but they charge WAY too much for that stuff where I live--$10 for a 12oz bottle).