Reducing image size in gimp vs other program

[snowforest]

If I reduce the size of an image with gimp vs another program, to the same size (just the scale or resize thing), why does the quality look different? For example I have an image I reduced its size with gimp. The lines looked faded a little. Then I tried reducing the size of same image with ms office picture manager. The lines looked less faded. Am I doing something wrong or is it normal?