Public grants are awarded by national and local government and government agencies, while private grants are funded by foundations or family trusts unassociated with the government. There are advantages and disadvantages to both types.
Advantages of public grants
Public grants usually offer larger sums of money. Also, accessing information about these grants, such as deadlines and application forms, is often easy.
Advantages of private grants
Private grants are easier to get and more likely to be awarded to individuals. Also, the application process is usually simpler.
Disadvantages of public grants
The application process is more bureaucratic, and competition is tougher because of so many applicants.
Disadvantages of private grants
The grant amounts are generally smaller, and finding information usually involves more research time.
The advantages and disadvantages are relative to your purpose and time line. For instance, experimental or start-up requests would find it disadvantageous that public grants tend to favour established, low-risk programs. But an established organisation with long-term goals that help certain segments of society could benefit from public grant funding. Conversely, an independent filmmaker seeking funds for producing a documentary would probably benefit more from private grant funding.