Both quizbowl and Reach for the Top are played by high-school teams on buzzers, answering questions to score points. Lots of teams in Ontario play both games.
Quizbowl is more challenging and more competitive than Reach for the Top, and quizbowl encourages some deeper learning.
Reach is a faster game, and it includes things like one-clue questions and spelling questions, so it is often preferred by casual players and junior players. Quizbowl has more questions about topics like science and famous books, so it is often preferred by strong students and readers.
Quizbowl can be great training to excel at Reach for the Top, and lots of volunteers work on both kinds of tournaments.
In Ontario, quizbowl and Reach for the Top both ask many questions on Canadian topics. Historically, quizbowl has been played on American questions, but now, we always arrange to swap extra Canada questions into every round of quizbowl. Reach for the Top probably still has more Canadian content in total.