Performance bonus: Meta pays annual bonuses as a percentage of base salary. E3-E4: -% target. E5: -% target. E6: -% target. Actual payout depends on your performance rating.
Signing bonus: Ranges from \10$100$K+ (E5+). One-time payment in your first month. Taxed as ordinary income.
The signing bonus often bridges the gap during your first year before equity vests (cliff period). If you're leaving unvested equity elsewhere, Meta may increase it.