Guess what? Popes John Paul II, Benedict XVI, and Francis don’t disagree a lick on the “key issues” of “same sex marriage”, celibacy, Islam, relationship with Jews, social justice, the environment, and technology.
(By the way, I’m fairly certain that Benedict XVI did not release an apostolic exhortation in 1981.)
I’ll go out on the limb and hazard they also don’t differ much on secondary issues such as the Trinity, Jesus Christ, salvation, the Church, the sacraments, Mary, and so forth. Again, just a cautious guess.