Terrified And Petrified

They do sound the same, and more or less give people the idea of experiencing fear. However there is a difference between them, else why should we have two different words in the first place?

Terrified is a past-tense verb which refers to getting frighten or menaced, or being in a state of intense fear. Example: She is terrified of her boss.

Petrified is also a past-tense verb, but it usually indicates  the loss of movement or being stunned due to fear. Example: She is petrified by the sight of blood filling up the bathtub.

Petrified has another meaning which is not commonly used. An action to convert organic matter into stone-hard material. However, to make things simple, I would usually prefer to remember Petrified, based on the first definition. Hope I have made your day by introducing the correct meaning for the words, and one less chance to get embarrassed by using them wrongly.