SQL Server Resource Pool and Workload Groups
Yes, those two scenarios will result in the same resource allocation - in theory.

In scenario 1, if there is CPU pressure, the two workloads running in the "20% resource pool" will share that CPU "equally."  How equally they are able to share the 20% can depend on a lot of things that are workload specific, given how SQL Server's scheduling algorithms work.

In scenario 2, if there is CPU pressure, the two workloads running in the "10% resource pool"s will each get a minimum of 10% of CPU time.

You have a better chance of a "fair" split of CPU in scenario 2, but scenario 1 could work depending on your specific workload.