What are the characteristics and limitations of SUM's Single System update strategy?

What is the difference between a Support Package Stack (SPS) and a Feature Package Stack (FPS) in SAP S/4HANA?

Why is it recommended that all systems in a landscape use the same update strategy?

When planning an add-on installation in the maintenance planner, what is the key difference from planning a normal update?

How feasible is uninstalling an add-on?

What is SUM (Software Update Manager), and which version does S/4HANA use?

What must the backup before update downtime include, and why include the SUM directory?