"The garden is not big."

Translation: Le jardin n'est pas grand.

[MaureenPow3]

I answered, "Le jardin n'est pas gros," and was marked wrong. What is the difference between "grand" and "gros".

[Sitesurf]

"Gros" is a 3D notion (think of "voluminous") and "grand" a 2D notion: size in height, length or overall surface.

[artigaujp]

Grand can also be one-dimensional : un grand homme : a tall man.