Yes There is a vast difference in smell between the two, as cat urine contains unique acid crystals and ammonia.
Yes, prolonged exposure can cause mild nausea and other symptoms similar to allergies. It is also not good for woman who are nursing, pregnant or may become pregnant to clean a litter box, this would...
NOOO, simply clean the spot, it won't hurt you or your loved ones.
No, it is not. Cat urine may smell terrible, but it ultimately won't hurt you.
Nothing? Burning at most.