Without giving too much away, I used to work for AWS (ironically, I've also taken a CIA polygraph, the two processes differ greatly).
1. Recruiter reaches out to you and asks basic questions.
2. A technical screen from a member of the team, more in-depth questions to get an understanding of: are you're qualified for the position? What level should be at? And so on.
3. A day of five interviews back-to-back with a lunch break in between.
Interviewers are often looking at how to place you (downlevel, uplevel), what team or project you can work on, and so forth.
Some general advice...
- Tell stories, SITUATION/TASK/ACTION/RESULT (STAR Method) is huge at Amazon, and they mean it. Situation: Here is the problem, Task: Here is what needed to be done, Action: Here is what I did, Result: Here is how it improved the company.
- Always talk about what YOU did, not what the team did, YOU. Be selfish.
- Answer the next question before the interviewer even has a chance to ask it. If you begin telling a story or detailing a scenario, you should be leaving no stone unturned. I would prepare 5 minute anecdotes and anticipate what follow up questions can/will be asked.
This ain't some seat of the paints joint. You will be required to communicate and explain yourself, especially as you advance in your career.
Their interviews aren't fun, but they aren't interrogations. I don't like how almost every interviewer I've dealt with is non personable. I don't know if it's a guideline for them to be sort of closed off or if Amazon has just broken them

.
Again, this ain't some corner store shoebox operation with a few servers here and there. Amazon's scale (there are numerous RFCs created for companies like Amazon, patent holders, and so on) )doesn't allow for a lot of, "yea, I like this guy." It opens the company up for operation issues (this person is not capable of doing this job at this scale) and legal issues (hiring bias, making decisions based on "feeling" or some shared connection versus using the data).
Interviewing requires training and shadowing at Amazon, it's a process.