@immychan From my experience it's mostly about RAM speed - L5 has LPDDR4-3200 while PinePhone has only LPDDR3-1333 which is further clocked down by stability issues (I believe most distros have it at 1104). For some workloads it's also the GPU - L5's GC7000L is much faster than Mali-400.
(technically both phones actually contain RAM that's capable of being faster than that but LPDDR4-3200 and LPDDR3-1333 is what their SoCs limit its speed to)