Schubert was a melody machine. Schubert was a tortured human. Schubert as a teenager wrote fresh, engaging music that you can listen to 100 times without getting tired of it. Schubert produced more music in his 31 years than Papa Haydn in his 77 years--Well, maybe not quite. Haydn was successful in the music business, with commissions and patronage from royalty. Schubert never had a patron or a steady income, and didn't have the temperament or the attention to negotiate with publishers or performance venues. Luckily, he had friends who arranged for publication of music, funneled the proceeds to him and paid the arrears in his rent.
Haydn was often light-hearted and jesting. Schubert never tried to be funny, but so much of his music is joyous, remarkable when we consider the pain he was in and the death sentence that hung over his young life. Haydn wrote 104 symphonies. Schubert wrote 600 songs, 9 symphonies, 6 Latin masses, 15 string quartets, 22 piano sonatas, only half of which were completed. The Unfinished Symphony was actually complete in two movements, but there were many, many other projects left unfinished as he worked feverishly, anticipating death from syphilis. He became expert at enjoying musical and social evenings in the company of friends during the intermittent remissions from his disease. He also spent day after day composing music as fast as it could emerge from his pen. Some of it is pedestrian. Some of it is overblown. But enough of it is inspired to assure his place among the historic masters. Wikipedia list of Schubert's works.