SPRINGFIELD — Two casino ­industry heavyweights, Penn ­National Gaming and MGM ­Resorts, promised to create jobs and drive economic activity in this struggling city, in dueling presentations to local voters Tuesday that launched the public competition for casino development rights in Springfield.

MGM came armed with the more detailed presentation, including short “walk-through” animations of its $800 million gambling, entertainment, and housing proposal, planned for three blocks in the city’s South End.