Rosewood will be a bit warmer, and maple will be a bit brighter.
Another thing to consider - Maple fingerboards MUST be finished if you want them to last. This has a number of fairly major problems, most importantly is that they are financially completely unreasonable to refret. You will eventually wear away the frets to some degree (unless of course you have stainless frets, and even then you may wear them away, we just haven't seen them for long enough to be sure. They will certainly last a lot longer though.) When you do wear away the frets, you can get a fret dress the first time or two (or three or four, if you get big frets), but then it will need a refret. On a rosewood board that is still a $300 job, which is an awful lot, but on a maple fingerboard it is $500-600, which is only ever resonable on the most valuable of vintage fingerboards (and even then only if they have been refreted before, as a refret will affect the value of the neck - and yes I think that is fucking idiotic, but the real vintage freaks want their stuff ORIGINAL, even if it is so fucked up it is useless).
Oh yeah, and if you want the brighter sound without the future repair issues of maple, plus most of the feel of rosewood (it is different, but it is still bare wood) look at ebony. Of course, the look is more like rosewood (particularly if you use a real strippy piece such as Macassar Ebony).
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