What is the difference between glaives voulges pole-arms and forks?

Answer 1

All of them are pole-arms - a polearm is simply a weapon type that includes a wooden pole or haft as part of the weapon.

The military fork is simply a long spiked fork, usually two prongs, on the end of a haft.

The glaive and voulge are visually very similar, both are a long cleaver-shaped blade on the end of a haft. The difference is that the glaive is generally mounted with a long socket, and has a projecting spike or hook (often very elaborate in later ones) on the back of the blade.

The voulge, in contrast, is mounted with metal straps which wrap around the haft, and sometimes run down it as well.