What is the difference between a counting stat and a rate stat?

A counting statistic totals events; a rate statistic places production in the context of opportunities. Passing yards, receptions, tackles, and touchdowns are counting stats because they accumulate as plays and games are completed.

Completion percentage, yards per attempt, catch percentage, and yards per carry are rate stats. Counting stats show total production, while rate stats can make players with different workloads easier to compare. Both still require context such as role, sample size, and game situation.