For the US, we have pretty detailed record keeping of how many slaves were imported, but for North Africa we do not.
The number of African slaves imported to the US is about 300,000, only a fraction of the approximately 12.5 million that were brought to the Americas in total.
As for the number of white slaves brought to North Africa, it depends on whose estimate. OSU news reports:
Most previously estimated slave counts have thus tended to be in the thousands, or at most in the tens of thousands. Davis, by contrast, has calculated that between 1 million and 1.25 million European Christians were captured and forced to work in North Africa from the 16th to 18th centuries.
(If you believe Davis, the claim is true. If you go with other estimates, it’s not.)
Davis’s high estimate has been criticized by other historians because “the corsairs also seized non-Christian whites from eastern Europe and black people from western Africa” and “modern estimates are based on back-calculations from human observation”.