Probably, hard to tell, the biggest difference, is Redis is likely storing the JSON as a string, and Posgres is storing it as binary json (separated out into distinct values/collections). I'd guess if Postgres was using UTF8 text for the JSON it would be closer. Also, Postgres is probably a bit less efficient on persistance requirements in favor of higher stability and preventing data loss.

In any case, Redis is probably a more natural and better fit (remote API result caching). That said, the comparison is awkward at best. If it were to cache localized results, where the dbms (PostgreSQL) is the source of truth, then adding a caching layer above the db may or may not be worth it.

I think the performance comparisons come down to Granny Smith Apples vs Rome Apples... you can bake a pie with either, but they don't taste the same.