Mathilda becomes overwhelmed with killing Stansfield, but she ends up getting captured when putting her plan into motion. Leon rescues her and kills two of Stansfield's men. Stansfield decides to go after Leon, by using Tony to find him. He orders a large crew of police officers to grab Mathilda outside Leon's hotel room, and use her to get to him. Leon kills many of the officers before deciding to get Mathilda out alive. He sneaks her out through an air vent, and dresses up as one of the dead cops so that the other cops can take him downstairs. Leon literally walks out of the hotel unnoticed, but as he is leaving Stansfield appears behind him and shoots him. Leon delivers a message from Mathilda to Stansfield by pulling the pin on a number of grenades attached to his chest, blowing both of them up. Mathilda goes to Tony to get her money, but she always wants a hitman job. Tony turns her down. She then goes back to the school that she ran away from earlier and plants Leon's much-loved plant in the front garden.
Answer: According to IMDb.com the title was only changed in the United States and the reason why was maybe audiences would find the title, "The Professional" more appealing than "Leon."
Tobin OReilly