Business Analyst role is not entierly different than Project manager role but Project Mangaer is more bigger role than business Analsyst.
Project manager is responsible for all the deliveriables like
- schedules/ timeslines
- resources management
- risk management
- Daily/weekly status report to project stack holders etc.
where as business analyst sometimes report to project manager or may report to business manager.
Business Analyst deals with business users to gater requirements, prepare RD,FD and coordinate with development team for development and then do the testing inolve with users in testing get the sign off and move component to live environment.

I hope this clearify the roles of PM & BA.