What is a Belgium horse and a Clydesdale horse?

The Clydesdale is a native breed of Scotland, similar to the Shire it's a heavy Draught Horse and was used for agriculture and pulling heavy loads such as brewery trailers/traps. Although big in stature they are noted for their docile temperaments.

They were also used in war time and there is still a Clydesdale used in ceremonial duties as a Drum horse in the Household Cavalry.
They are now mainly used for showing purpose's. The Rare Breed Survival Trust has the Clydesdale listed as "At Risk" but this is an improvement as in the 1960's/70's it was classed as "Vulnerable". A Clydesdale stands between 16hh-17hh but the current world record stands at 20hh.

I don't know much about the "Belgium Horse" if you mean the Brabant/Belgian Draught then I don't know too much about them but they are very similar to the Clydesdale reaching the same height as them and are used for the same types of work, they are actually still used in agriculture. They are much shorter in length than the Clydesdale and have smaller heads and shorter necks.