A fugue is a specific form of in which one instrument or voice states a musical idea and then the other instruments or voices repeat the musical idea. While the other voices are repeating the idea, the main voice continues, which forms an accompaniment to the other voices, forming one large sound texture.
A sonata form has at least three different sections, or movements: introduction, development and recapitulation. Some sonatas use one instrument; others use up to three instruments. Sonatas composed from 1600 through 1750 often had four or five movements, each with different tempos, often performed as a dance.
A concerto is characterized by a single instrument which carries the main theme of the music, accompanied by an orchestra. Concertos are written to display performers' skills with their particular instruments. Concertos are similar to sonatas in that they contain three movements.
In a cantata, vocalists sing with musical accompaniment. It is characterized by sections where the vocalists speak melodically, instruments play for a period of time and then the vocalists sing. Cantatas are similar to operas, but are usually shorter.
A symphony is divided into three sections, the first and last being fast in tempo and the middle being slower in tempo. Symphonies are played by a large orchestra, unlike with a sonata or a concerto where there are only a one or a few instruments.