A sole proprietorship is an unincorporated business owned by a single individual. The business and the operator are the same.
It’s the simplest (and therefore most popular) structure, with minimal or no setup requirements. Your business losses can be deducted from your other sources of personal income. However, this structure only works for a solo dev. You’ll face unlimited personal liability and challenges raising money. Bootstrapping (using your own money) or loans are possible sources of startup funding.
A partnership is the same as a sole proprietorship, except it’s between two or more people. General partners also risk unlimited personal liability, and you’ll have difficulty finding appropriate financing.