WHEN ADJECTIVES CHANGE THEIR MEANING"
Some adjectives change their meaning when used with either "ser" or "estar".
Spanish ser

estar

listo clever ready
malo bad ill
rico rich tasty (for food)
vivo lively alive
bueno good well (in good health)
cansado tiring (person) tired
grave serious (personailty) seriously ill
verde green unripe
moreno dark-haired suntanned
pesado heavy (thing) boring (person)
seguro safe sure, certain (person)