System Demo vs sprint reviews
I am a bit confused about the difference between system demos and sprint reviews. They sound the same to me and a bit repetitive. System demo is all about showing what the teams, on one ART, have worked on in the recent iteration to stakeholders, customers, business owners, etc. I understand that the system demo is more of a integrated demo and it shows all the components put together. Sprint reviews are more on team level, but it has the same purpose where you have customers, business owners, etc and you show them the MVP that you accomplished this recent iteration and you take feedback back to the teams. So what is the benefit of a system demo? Wouldn't you get the same feedback, same audience, etc.? Ultimately wouldn't the main purpose of both meetings would just be to take away positive/constructive feedback?
It sounds like you're talking about Scaled Agile Framework (SAFe) so my response to that question will be through that particular lens.
The assumption here is that you have multiple teams working from a single product backlog. Someone can correct me if I'm wrong here but I don't believe SAFe calls for an integration of all the teams increments until the end of the program increment which is the reason for the system demo. So the Iteration Review would be at the team level as you mentioned, however, their work may not be integrated with the other teams yet. The System Demo is essentially the same thing but all of the team's work should be integrated together at that point.
To address the last part of your question, yes you'd likely get the same audience they would just be viewing an integrated demonstration of the end to end system. I'd almost look at it as a picture cut in half. During the iteration review the stakeholders may see the left side of the picture and during the system demo they would see the left and right.
If you're following a Nexus framework the Scrum teams would be required to produce an integrated product backlog increment of all teams each and every Sprint (thus a 'system demo' would not be necessary).
This definitely seems like Scaled Agile Framework (SAFe) to me.
In SAFe, an Iteration Demo (their analogy to the Sprint Review) is held at the team level while the System Demo is held at the Program level. Both occur at the end of every iteration. At the Iteration Review, each team will demonstrate their work to the Product Owner and receive feedback on it. This event caters to the stakeholders of each team, which may include other teams. The System Demo is at the Program or Agile Release Train level and caters to the stakeholders with an interest in the output of the ART.
In my experience in scaled (multiple teams, one product) environment, this is duplication. I prefer the model from Nexus or LeSS where all of the teams working on a single product have a unified review at the end of the Sprint or iteration. This is much lighter weight in terms of process and I believe provides a solid foundation. If a team believes that they would like to get together and hold a review and optionally invite stakeholders, that is their decision and I don't see any reason why it would be prohibited.
I am a bit confused about the difference between system demos and sprint reviews. They sound the same to me and a bit repetitive.
Can you clarify the sources you are using, and through which confusion may have been caused?