ETS has published “Beyond Score Correlations: A Content Comparison of IELTS Academic and TOEFL iBT® Tests in the Context of a Score Concordance Study.”
The report compares the content of the IELTS (Academic) test and the old TOEFL that was discontinued in January. It is a good read for folks who are interested in this sort of thing, but perhaps not so useful for score users in 2026.