Scientifically the differnece between a fruit and a vegitable has to do with the Seeds, Im not exactly sure, but it has to do how you get seeds.
You can get tomato seeds from a tomato, however you cannot get Radish Seeds from a raddish.
Haetz or Hadama has nothing to do with a fruit or vegitable, but rather how the item grows. Something that grows in a tree is Haaetz and something that grows in the ground is Haadama. An Avacodo is Haatez and a Melon is Haadama