Currently looking at timing for an on prem upgrade/

The current Roadmap lists this "User Rows and Columns in Universal Reports | Report authors can add their own rows and columns to be tracked in the report. These rows and columns allow for the use of Excel based calculations."

PAfE 104 release notes: Add spacer rows and columns to Universal Report

Anyone aware of the distinction?

Hello,

It's a very subtle difference indeed. Spacers is the 'MDX' solution to insert blank spaces between rows and columns (for the sole purpose of formatting a view as a financial report). In the context of excel, the advantage of a spacer compared to a user inserted row/column is that the spacer is part of the MDX query and can follow the dynamic pattern that you've set for the view.

Let's take the following example: I want to display YTD/YTG/Year for a set of scenarios. 

The view is bit hard to read, so I want to add spaces between scenarios. The problem is that the number of scenarios isn't fixed and I don't want to manually add new spaces each time I add a new scenario. The solution is add a spacer before 'YTD June' so that it gets repeated for each scenarios. 

The reason it gets repeated is because a spacer is actually an empty MDX calculated member, so it acts as a dimension member and not a fixed element outside the view

Excellent answer, understood. What I'm really looking for is to have the query to respond with just Skeleton data as I would with Dynamic reports. So we'll wait a bit longer.