Power BI is a tool from Microsoft, mostly unrelated to Power Query (although you can pull data from Power BI into Excel via Power Query, but you can also do that with just about anything tabular).

https://powerbi.microsoft.com/en-us/

"The first release of Power BI was based on the Microsoft Excel-based add-ins: Power Query, Power Pivot and Power View" (https://en.wikipedia.org/wiki/Microsoft_Power_BI)

Power Query is the only part of this that has seemed useful to me.

The Data Model and DAX in particular seemed to me like distractions that I wasted time on before discovering the M language.

Saying Power Query is mostly unrelated demonstrates that the confusion is not all mine.

PowerBI is kind of a MS Access for BI. It loads data from your warehouse and gives both visual builders and query interfaces to data. IE, it's a specific product name - the data viz tool from MS to accompany their other services.

It seems to be part of Excel since 2016, no? It appears to me that it's morphed over time and I'm not sure to what extent it remains a separate product.

I've used both DAX and M (Power Query) via recent versions of Excel. Obviously there are plenty of ways to interface with data.

https://en.wikipedia.org/wiki/Power_Pivot says both Power Query and Power Pivot are part of Excel.

It's a separate product, analogous/competitor to Tableau. Just go to the product page

I assume you're referring to https://powerbi.microsoft.com/ ?

What I'm seeing there looks as though it is targeted at people who make the decision to buy products like this, but not to use them. I'm not seeing what couldn't be done with Excel 365 alone. There are screenshots with verbiage about how well it works with Excel. And they look like...Excel.

I guess it supports R, and maybe makes it easier to seamlessly refresh a report. That's aggravating though, that it makes me suspect Excel might be purposely rough around the edges in order to not displace Power BI.

As I've said a few times, I like M and wish they'd commit to it.

I honestly suspect Microsoft is repackaging functionality that already existed for many years in their "ball of mud" software, with a shiny new wrapper and better defaults, but practically unusable, because people who license software are easily manipulated.

Power Automate is the most awful example of this I've used so far.

You say it's a competitor to Tableau, well, Tableau is a competitor to Qlikview, and I've used Qlikview and Excel enough to consider Excel better in every way that I care about. (My organization uses SharePoint, so that's how reports are usually distributed)