What is the difference between "grajno" and "greno"?

Question

I cannot find out the exact difference between the Esperanto words "grajno" and "greno", they both translate to the English word "grain". So, what is the exact difference between both words?

Answer 1

greno is the general expression for crop/cereals as plants and raw material (tritiko, hordeo kaj sekalo estas speco de greno, tiu kamparano ne bredas bestojn, sed kultivas nur grenon).

grajno is the grain you get from the crop (or similar plants, e.g. grajno de kafo), the concrete granules (al mi plaĉas pano kun plenaj grajnoj).