This list updates weekly.
The New York Times bestsellers list uses data from both independent booksellers and major companies like Barnes & Noble and Amazon, along with other markets, like supermarkets, gift shops, and newsstands. The way the New York Times actually interprets or weights this data is unknown, but probably not just directly based on raw sales numbers.
This list updates weekly.
The IndieBound list is compiled by the American Booksellers Association who use data reported by a large number of independent bookstores. However, titles are ordered by their average sales rank at individual bookstores instead of by overall sales numbers. That means that a book which technically sells the largest number of copies may not be at the first spot of the list if it was not the bestselling book at the majority of independent bookstores. This gives a lot more swaying power to smaller booksellers.
This list updates weekly.
Publishers Weekly pulls its data from the BookScan service, and orders its list according to raw sales numbers. BookScan pulls data from approximately 75-85% of all printed book sales in the US, including sales from major booksellers like Amazon, Barnes & Noble, Walmart, and thousands of smaller independent bookstores as well.