Comparing Human vs. Human
A variation every ~1000 nucleotides.
99.9% have 23 chromosome pairs, at least initially (others tend to have infertile offspring)
90% of human variation is within African populations.
There are enough humans, and the mutation rate is high enough, that on average each base is mutated several times in each generation.
Humans each carry hundreds of negative mutations. Luckily most only are recessive and only show up with inbreeding.