You can probably pretty easily just say Prime==Performance and Performance==Efficiency, but I think the "Prime" branding is kind of a carry over from Snapdragon mobile chips where they commonly use three tiers of core designs rather than the two. They still want to advertise the tier 2 cores as fast so T3 is efficiency, T2 is performance, T1 is Prime.
As an example, the Snapdragon 700-series had Prime, Gold, and Silver branding on it's cores.
Not sure what a prime core is.
For comparison the M4 Pro can go as high as 10 performance cores and 4 efficiency cores.