All major league contracts are guaranteed. So are NBA. NFL contracts are not guaranteed.
Not all NBA contracts are guaranteed. Many players must earn their roster spot to earn their money. One example of this is that first round draft picks have guaranteed contracts, but draft picks after that must make the team before or their contracts are terminated.
The difference is the Union. The NBA have guaranteed salaries in their CBA (Collective Bargaining Agreement). The NFL does not have clauses that guarantee the entire salary, but the signing bonuses are the guaranteed portion of their contracts.
No contracts are guaranteed.
All pro sports except for football have guaranteed contracts.
No. Guaranteed contracts are forbidden under the NFL's bargaining agreements with its players. Guaranteed portions of contracts are allowed, as are signing bonuses.
Not all of them
They are guaranteed a profit.
as much as it says in their contracts