All fruitcakes, and fruitcake recipes, are not the same.
Fruitcakes of different countries and cultures are completely different. Traditional English fruitcakes [and English "colonies"] mostly do not include large amounts of most candied fruits , and citron is not a part of most recipes. Citron, especially, can be virtually unknown.
Of course, there are recipes that include candied fruits, pineapple, citron etc. They can be made using a "boiled fruitcake" technique, time-saving techniques [cake mixes], and lots of other ways.
Fruitcake is fruit with just enough traditional pound cake batter to hold it all together
Fruitcake is NOT torted, layered ar filled with anything. Buttercream is NOT the cake covering for fruitcake.
Most celebratory cakes are liberally doused with alcohol.
Fruitcake needs approximately 12 weeks to mature [definitely!]. Preserative of choice is usually alcohol. [12 weeks is usually minimum aging period].