OPK vs. basal thermometer

Stacie • Mother to Ben 👦🏽, Bash 👦🏽, and Braxton 👶🏽, 420 enthusiast 🔥💨, lover of life 😍🤘🏾
What's the difference between an OPK and a basal thermometer? Don't they both just tell you when you're going to ovulate?