I've always seen a fursona as the animal character you have that you identify as. For instance, in the world of Feralheart, I go by Edol, the German shepherd, or Tooth the lion. In short, yis, I guess you could say a fursona is sort of your 'main' charrie/charries, while a character is 'an illusion of a living being which is created in the mind of an artist', as was so brilliantly explained by Jenga <3