It don't think it ended the war. It was however the reason that America chose to join the second world war. Before that America was hesitant to involve itself in 'Europe's issues' and only participated by lending money to some countries involved in the war.
After the Japanese bombed Pearl Harbour the US took it as a person offence and direct attack against American, and joined the second world war alongside the allies (England, France, etc..). Many say that Americas involvement was a big component to the Allies winning the war.
The bombing of Hiroshima and Nagasaki in Japan were however the bombings that truly ended the second world war. This was done by the allies as the Japanese refused to surrender.
