That there are differences between the world's major racial groups should come as no surprise when you consider the differences that occur even within one racial group; or often, even within the same country.
For example, when we first arrived in Papua New Guinea (where the expatriate community of 25,000 was dwarfed by the local population of over 5 million), all Papua New Guineans looked the same. However, before very long, one got to be able to identify by their appearance which part of the country a person came from. (The capital city, Port Moresby, contained people from all over the country, with the customary land owners - the Motu people, being quite marginalised).
These regional differences include hair colour; one whole tribal group - the Tolai people of East New Britain - are often blond haired, as are their neighbours across the channel in New Ireland (Only the nose gives the Tolais away. Theirs is a typical flat, broad, Melanesian nose - while the people of New Ireland have a straight, almost aquiline nose). Amongst other Papua New Guineans, red hair is by no means uncommon. And before some smart-@$$ suggests that this all came about because "Granny went out with sailors", blond-haired people were already resident in Papua New Guinea when the first sailors arrived there.
Other physical differences include size and shape, from the sturdily built people of Enga Province to the pygmy-like Watut peoples of Morobe. These differences aren't all physical, either. People also vary considerably in nature . Those, however, could fill a book, and I won't start now! Then there is the tremendous variety of languages spoken in that country. By the last count that I heard , these number at least 806.
So as to whether there are greater variations within the white races than any others, I am not at all sure.