One similarity is that both religions are made for, and often attract, R&F members who are incapable of thinking, or do not want to think, very deeply re: theology.
That said, Vidiot's comment
Easier and quicker to make a list of how they’re not similar
has considerable merit. For example, many Catholic priests, especially genuine scholars, express disagreement with the Church's official line on various doctrinal matters but retain their positions. A Witness elder could never get away with that.
R&F Catholics do so too. One Catholic language instructor I know used to do that in the classroom about required celibacy for priests and openly say that it was a cause for sexual immorality among the priests. He hated Vatican II and openly criticized it. Yet every Sunday he attended mass and received communion. The RC Church has far more tolerance among its membership than does the WTB&S, even if we leave out obvious areas like accepted fornication and mafia membership.