You can attract heavy fines from CRA and the courts if you have discrepancies in your returns. Tax frauds are dealt very seriously by Canada, and legal action can result in heavy gross negligence penalties or criminal proceedings.
Based on your offence, you may need to pay a penalty between $1,000 and $25,000. In 2016-17, the Canadian courts imposed $10 million in fines and 50.5 years in jail term for various tax offences.
Using VDP, you can get complete relief from paying penalties if you are simply trying to correct unintentional errors. However, if you have reported or withheld information intentionally, you might need to pay reduced penalties. But even then, you can get protection from criminal prosecution and gross negligence penalties.