What is the difference between balance and total earned?

Points Balance is your current spendable points - the points available right now to redeem for rewards. This decreases when you redeem points for rewards.

Total Earned is your lifetime cumulative points - every point you've ever earned from all your charging sessions. This number only ever increases and is used to determine your tier level.

For example, if you've earned 5,000 points total and redeemed 3,000 for rewards, your balance would be 2,000 points, but your total earned would still be 5,000 points (which determines your tier).