Grdmath subtracting 2 grids of different sizes


I’m trying to subtract A.grd from B.grd using grdmath in order to spot differences between them; however, these grids are different sizes, so when I run the command:

gmt grdmath A.grd B.grd SUB = subtracted.grd

I get an error: grdmath [ERROR]: grid files not of same size!

A.grd has: Longitude n_columns: 8042 and Latitude n_rows: 2990
B.grd has: Longitude n_columns: 8010 and Latitude n_rows: 2987

Is there a way to make these the same size so that I can subtract them? Any advice is helpful, as I am new to GMT!

Thank you.

Yes, see grdsample