Answer: They are similar because they both have a common ground and are both principal to their tribes and colonies.
Step-by-step explanation:
The Monroe doctrine was a doctrine used to oppose European colonial in the United States. It was a united states policy that started in 1823 in the US. The US had pledged to eschew from European business and also wants Europeans to do the same in the Western Hemisphere.
Adams-Onis Treaty also called "Transcontinental Treaty" that started on February 12, 1819, this treaty was adopted to settle border issues which involves the Spanish empire and the United States that really helped national security. What really lead to this treaty was the constant border raiding by Seminoles out of Spanish Florida. This treaty in Spanish is "Tratado de Adam- Onions"