Whole image fits the complete photograph inside the selected rectangle. Crop to fill covers the rectangle and removes some edges when the ratios differ. Look at faces, text and horizon lines in the preview. A white border creates space around the image but does not restore a cropped subject.
Crop and white border
The white border sits inside the chosen outer dimensions. Whole image keeps the source ratio, so additional blank bands may remain. Crop to fill removes edges, and crop zoom removes more detail without changing the physical print rectangle. Use the position sliders to protect the subject.
Before you print
Use Actual size or 100% in the PDF print dialog. Match the paper format and disable any further resizing in the printer driver. The preview shows the PDF layout, not a guarantee of your printer’s printable area. Start with ordinary paper and measure before using photo paper.