Just want to know which one is better, or is there much difference between the two? Sound wise and quality wise.
quality of both can be excellent or crap depending on the grade of the wood. don't expect a squier affinity maple neck and a suhr maple neck to sound alike. the main difference is tone - maple is brighter.
Fretboard plays so much importance in tone? Find it hard to believe based on physics - the actual mass is the wood in the neck, not the fretboard. The vibrations and resonance should be dictated more by that, than by the fretboard material.
Well maple won't offset mahogany but it will make an alder body sound brighter than with a rosewood fretboard. That much difference I'm sure you can notice.
though body wood/pickup configuration have their own dynamics, maple will be brighter and rosewood darker. also maple is physically much smoother to play - because it is finished while a rosewood fretboard is not. if you want a rosewood look with a maple feel, you can try pau ferro.