The Jedi Academy is the first step toward becoming a fully-fledged member of the Order. Within the Academy, you will face various tests and trials that will determine how quickly you learn, your abilities, and your interests. You'll start out in the Order as a Force Sensitive. In order to progress, you must join the Jedi Academy.
As mentioned previously, the Academy exists to prepare newer members for the responsibilities that may fall upon them later as they move up through the ranks, and to provide them with as many experiences as possible so they can choose the path they want to take. Opportunities vary from becoming a teaching student in the Academy or Service Corps - This can range from being a Lightsaber Instructor to lore experts, and so on. You can also apply to the Librarian's Assembly, which manages the Order's Archives on Naboo, or the Diplomatic Corps [DESCRIPTION TBA]. Otherwise you can apply for the Taskforce, which is the Order's direct connection to the Clone Army of the Republic, or apply for the Temple Guard, the most elite and prestigious division the Order has to offer. Everything starts from your journey in the Academy.
Youngling I
Youngling II
Youngling III
Ranks Youngling I -> Youngling III are the primary educational phases mentioned prior, and are half the focus of the Academy itself.
Graduated
Teacher
Graduated signifies you passing all of the tests and trials as a Youngling, and have free reign to try the other paths available to you. Teachers within the Academy are those who chose to dedicate themselves to educating newer members, and are on their way to becoming Jedi Instructors.
Instructor
Deputy Headmaster
Headmaster
Instructors are trusted members of the Order, who have proven themselves knowledgeable in various key topics and history points pertaining to the Jedi Order. The Headmaster and Deputy Headmaster oversee the Academy itself, directing their team of Teachers and Instructors, ensuring that the Academy is running properly.
Obviously, you will eventually have to leave the Academy and will be given two choices. Once you've reached the rank of Initiate, in order to progress you will be required to:
Find a Jedi Knight+ to take you as their Padawan
Enlist in the Jedi Service Corps and become a Stage II Initiate
Joining the Jedi Service Corps means you will practically handle your own education and preparations for the Trials of Knighthood. You will be provided with various informative sources, regarding topics and key points you will need to know for your Trials, but you won't be bound to doing it on your Master's timetable. Instead, you control when you take your Trials, based on whether you think you've learned enough and gathered enough material to take them.
For more information on the Jedi Service Corps, go to this page:
Becoming a Padawan is similar to joining the Service Corps, except your education will be directed and supported by a Jedi Knight+, an individual that has already completed their trials and become a fully fledged member of the Order. Your Master will decide when you are ready to take your trials, and alone will be responsible for making sure you have all the necessary material.
If you choose to take this path, then you won't be required to join the Service Corps.