there are several types of hash, made and extracted in several ways...
the most common is afghani or mexican black or brown hash.
it is the lowest purity and is gathered by them sending their workers thru the fields, rubbing their fingers down the leaves on the buds... the thc sticks together to form brown deposits on their fingers which they scrape into a container with a dull knife. this hash is rather nasty as it is about 30% dead skin cells and bodily fluids.
The next is keif... this is not actually hash, it is made by scraping or shaking the crystals and hairs off of buds and then compressing it into bricks. very potent smoke with a very high purity, excelent choice if available... should be a light golden color with red and green specs thruought
the next is chemical extraction hash. it is extracted by butane, acetone, alchohol etc and is very pure. almost 90% thc
then, lamb's bread... i have no idea how it is made, but it is about half hash, half bud. it comes wrapped in aluminum foil and looks like either a golden, brown, or green candy bar.
there are several other types of hash, but i dont wanna list them all, just the most common