It depends, in some cases yes because often Mary I is called Mary Tudor but sometimes Mary Tudor may refer to Henry VIII's younger sister. Check dates and events around the Mary Tudor and you should be able to work out which one it is talking about.
Mary Stuart is not Mary Tudor. Mary Tudor (a/k/a Mary I of England) was born to Henry VIII and Katherine of Aragon. Mary Stuart (a/k/a Mary I of Scotland) is Mary, Queen of Scots, and is Henry VIII's grand-niece, and Mary Tudor's first cousin once removed.