Originally, the Bill of Rights applied only to the federal government. That is why, for example, the First Amendment says that it is “Congress” that cannot make laws abridging the freedom of speech. At that point, states were free to make such laws. This started to change when the 14th Amendment was ratified. That amendment said that states could not deprive people of their liberty without the due process of law. But what did this mean? Did it mean that all of the Bill of Rights applied to the states? Did it mean that part of it did and part did not? The three approaches you mention had to do with this issue.
The fundamental fairness doctrine holds that the 14th Amendment requires states to treat people in ways that are fundamentally fair. This is a vague standard. It does not say which parts of the Bill of Rights have to be upheld in order for states to be fundamentally fair. Courts are left to decide on a case-by-case basis if state actions are fair. This means that courts could leave out some of the Bill of Rights, saying that they are not essential to fairness, but could then turn around and say that things that aren’t in the Bill of Rights are essential to fundamental fairness.
The other approaches specifically look at amendments from the Bill of Rights and think about which ones the states need to follow. The doctrine of total incorporation says that all of the Bill of Rights applies to the states. By contrast, the doctrine of selective incorporation says that only some of the Bill of Rights applies to the states. This doctrine says that courts have to look at each amendment and decide whether it is truly essential to liberty. In that way, it is somewhat like the fundamental fairness doctrine because it says that courts have to decide what aspects of the Bill of Rights are really important.
So, total incorporation says all of the Bill of Rights applies to the states. Selective incorporation says only some of the Bill of Rights (those parts that are essential to liberty) apply. The fundamental fairness doctrine says that states cannot act in ways that are unfair to people, regardless of whether their actions are banned by the Bill of Rights.