There is no significant difference between jail and gaol because the two words are actually referring to the same thing. The main difference between jail and gaol will be explained using what the two words stand for and how acceptable is their usages through the world. Like I said before, the two words have the same meaning. Jail is an English word referring to a place specially made for prisoners.
The term jail is equally the same as prison in the US. Jail (gaol) is a place where some set of people who have been legally convicted are kept for behavioral modification. The idea behind the use of jail for prisoners is to restrict their freedom in order to stop them from committing the same crime or another one. However, the main difference between jail and gaol is that, the use of jail is very common in the US and most of the countries of the world, while gaol is used only in the United Kingdom and Australia.