What's the Numbers equivalent to Excel's "A1:A10-B1"

In numbers, SUMPRODUCT (range, range…) takes the following arguments:

range: A range of cells. range is a reference to a single range of cells containing values of any type. If string or Boolean values are included in range, they are ignored.

range…: Optionally include one or more additional ranges of cells. The ranges must all have the same dimensions.

So you'll need to set up a range to perform the initial calculation (and squaring) and then sumproduct two simple ranges.