The quality of periodical papers of IEEE is generally higher than that of conference papers. One of the most important reasons is that most IEEE conferences are not sponsored by IEEE, but by some schools or other institutions. These conference organizers submitted applications for publishing conference proceedings through IEEE, so IEEE only participated in the subsequent publishing work and did not send experts and scholars to participate in the paper review.
Of course, with so many press conferences, we can't generalize. IEEE Transactions is a recognized authority, and most of them are top journals in their fields. However, many IEEE landmark conferences are also very good, such as IEEE ICRA (Top Conference in Robotics), IEEE CDC (Top Conference in Control) and ACC (Top Conference in Control). These meetings are not better than some domestic EI periodicals.