The United States’ (US) foreign policy traditions since the dawn of 20th century can be divided into two broad perspectives — the realist and liberal. The realist tradition was set by the US president Theodore Roosevelt, while the liberal tradition was laid down by President Woodrow Wilson. Theodore Roosevelt tradition sees US foreign policy in the light of its interests and the US role in the world as per the concept of balance of power. It sees an international role for the US because it considers the world politics inconceivable without the involvement of the US, which it prefers to practice through military might. 
Theodore Roosevelt was the president of the US from 1901 – 1909. It was the time when the US was replacing the Great Britain as the world power, and it had gained a considerable economic and military might. Theodore Roosevelt wanted this power translated into practical measures to dominant international politics. Roosevelt himself participated in Spanish-US war in Cuba in 1898, and was later elected as president. While he was in power, he did not practice liberal ideals in Cuba for which they claimed to fight and gained victory; rather, he made sure that Cuba remained under US control for its interests and for showing Spain and the other powers in western hemisphere that they were not to interfere in American affairs, as per the Monroe Doctrine. He also saw the rise of Germany in Europe with caution and wanted to have a check on Russia in Asia.
Thus, the Roosevelt doctrine of foreign policy was based on real world challenges with no room for US idealist sentiments of grandeur and the responsibility of spreading the liberal and democratic ideals to the rest of the world.    
Woodrow Wilson foreign policy tradition is based on an idealist perspective. It considers the dissemination of US principles and the leading role of the US in the international political arena as a mission. It is not the balance of power that the US foreign policy seeks; rather it is exalted responsibility of US universal values that it wants to achieve.  
Woodrow Wilson was the president of the US from 1913 – 1921, through the World War I. He could see the European concept of balance of power and the struggle for military might alone had resulted into instability and later into a bloody war that lasted for four years and took millions of lives. Therefore, he saw no value in such a doctrine and wanted that his ideals of liberalism and democracy should be pursued as they could achieve peace and security. Based on the same principles, he gave his famous 14 points at the end of World War I that could achieve peace and stability. His points included liberal ideas like open diplomacy, no barriers on trade, freedom of the seas, disarmament, national sovereignty for weaker nations and creation of an international body for the solution of conflicts and wars. League of Nations and later the United Nations were formed based on the same concept. When the World War II broke out and resulted in the death of millions of people around the world, Wilsonianism received another appreciation. It was now the disobedience of the Wilsonian principles that the world had suffered such a great war; therefore, it was necessary to turn back to those principles. Thus, the World War II resulted in the formation of the United Nations, an international body with more importance and significance than the league of nations, but based on the same ideal principles. It was also realized at the time that since the Wilsonian principles were not followed with true spirit, like the national sovereignty and the open seas and economy were forgotten; therefore, an ideal liberal order could not be established. So, World War II was followed by the establishment of international financial institutions as well, that could work for reduction of poverty and financial support at the international level to avoid war and conflicts.
Wilsonian doctrine could be found during the Cold War Era as well, as US presidents like Eisenhower, Kennedy, and Nixon associated their ideas with those of Wilson’s. Cold War for these presidents were the fight of the liberal, democratic values against the non-liberal, authoritarian and dictatorial regimes led by the USSR. For them, these values were not important to defeat Soviets but to help the universal values of liberalism thrive for they were rightful to do so.  Disintegration of USSR in 1991, further paved the way for the Wilsonian tradition to thrive as it was seen as the victory of liberal democracy against dictatorship. However, since the dawn of 21st century and particularly after the war on terror and the financial crisis of 2008, the liberal democracy has been facing severe challenges. The international political arena has experienced a rise in global authoritarianism and the liberal democracy is, in fact, in a retreat.
The election of President Trump and the policies that he followed clearly showed a rise in authoritarian practices even in the US — the torch-bearer of liberal democracy. President Trump’s tenure was definitely a rebirth of the realist approach as propagated by Roosevelt foreign policy tradition. Trump strove for making ‘America great again’ even through the sacrifice of liberal practices for which the US stood for many years. He even challenged the role and authority of international organizations like the United Nations and NATO and withdrew from the international treaties like Paris Agreement on Climate Change, Trans-Pacific Partnership and JCPOA. Moreover, the trade war with China was also a foreign policy initiative that negated the very foundation of free trade and liberal world order.
Now, that Joe Biden has been elected as the president of the US, there are expectations that he would return to the Wilsonian tradition, and direct efforts to undo the damages done by the Trump administration. However, in the backdrop of the rise of geopolitics and authoritarian states in the international political arena, it would be a Herculean task for the Biden administration to achieve something remarkable.