Bloody Elizabeth?

Class Question:

Queen Elizabeth's predecessor, Mary I of England, is referred to by historians as 'Bloody Mary' because of persecution of Protestants in England.

Upon succeeding Bloody Mary, Elizabeth I established Protestantism as the official religion of Great Britain. She began her long persecution of the nation's Catholic's immediately after.

Question: Why is Mary I notorious for her persecution of Protestants, and referred to as Bloody Mary? Yet, Elizabeth I is referred to as Good Queen Bess, despite her long persecution of Catholics? Is this another instance of Tonypandy?

https://muse.jhu.edu/article/50912