Shortbows are ranged 2-handed weapons which require at least 6 Strength to wield them. Classes from the rogue-group and the warrior group can wield them. This type of weapon has a reach of 75 feet and attack rate of two arrows every round (6 seconds) and arrows as ammuntion.
Short bows were the first to be developed, although they were not called such. This is more of a default term that refers to anything which is not a long bow. Short bow staves are about 5 ' feet long on the average. As the years passed, attempts were made to increase bow ranges. Bows were either given longer staves or flexibility was increased with no change to the length. The former resulted in what is now called the long bow.