I'm not familiar with the current state of bigLITTLE, but at least initially, bigLITTLE clusters weren't capable of heterogeneous compute; you could shift between cache-coherent clusters (use either all four big cores or all four LITTLE cores) or have virtual cores, each made up of one big and one LITTLE core, with the kernel managing which physical core was actually executing threads assigned to the logical core.

My understanding of the A11 is that it's fully heterogeneous with the capability to run and assign code across any permutation of its physical cores.