Both concepts are very closely related to one another. The theoretical understanding of separation of powers is when the powers of government are parceled out to different branches. Consider the tree metaphor here. The base of the tree is where its roots exist and this is the element of power that gives reason to its being. The roots at the base of the tree represents the government's power. As the tree grows, the branches spread out and these branches represent the separation of powers in government. The branches are extensions and different reflections of the base power in government. Each branch is unique and represents the overall distribution of power in government.
A practical example of separation of powers is a government that has legislative, executive, and judicial branches of government. A legislative branch is the lawmaking portion of governmental power. The executive branch embodies the means of enforcing the laws of government power, and the judicial branch oversees the enforcement and construction of laws to ensure that they are operating within the framework of the founding charters of governmental power. The presence of these three branches in any government would be a practical example of separation of powers.
Checks and balances is closely related to separation of powers. In the checks and balances configuration, each branch of government is limited by the other branches of government. Checks and balances ensures that one branch is not too powerful in the exercise of government power. In the construction of checks and balances, power is seen as something potent that has to be limited so that it is not abused. To balance out power, it is limited or checked by other branches.
Checks and balances can be seen in the daily practice of government. For example, in the United States' configuration of government, the legislative branch is checked by the executive branch in that the executive branch signs into law what is agreed upon in the legislative branch. A bill from the legislative branch does not become law unless the executive branch signs it. Another practical example of this is how the executive branch is limited in the legislative branch's ability to make the laws. Finally, the judicial branch checks the power of both legislative and executive branches by declaring laws and acts unconstitutional. In this understanding, the practical elements of checks and balances ensures that the branches of government must work together in order to ensure the smooth functioning of the nation's exercise of governmental power.