What are signs of stroke or bell's palsy? can you get this when you're 15?

Stroke v Bells: Both of these conditions can cause facial weakness. Usually, but not always, a stroke causes weakness on one side of the face, of the lower face (mouth) only. This is apparent when someone tries to smile. Bell's palsy affects the upper and lower parts of the face, so it is hard to close the eye tightly shut and to smile, on one side of the face. There are always exceptions, but this is helpful.