Who won the War of 1812? Was it Britain/Canada or the United States?

The War of 1812 (1812–1815) was inconclusive. Neither side was able to make decisive gains during the war. America's greatest victory in the war, the Battle of New Orleans, actually occurred after the peace treaty was signed.
Negotiations to end the war started at Ghent (located in present-day Belgium) in mid-1814. The American delegation to the talks was led by John Quincy Adams (a future American president), Henry Clay, and Albert Gallatin. Negotiations were long and difficult. At the beginning of the talks, the British had just burned the Capitol in Washington DC, so they had a stronger position. But the American victory at Plattsburgh restored an equilibrium.
The two sides agreed to return any territory occupied during the war. The treaty did not address the real causes of the war. The war broke out because of disputes over neutral nations's rights on the seas, but the Treaty of Ghent did not deal with them. In any event, the War of 1812 was the last conflict between the United States and Britain.