You could use dried fruits, like dried cherries, apricots, or cranberries. But if I would pick one, that's my thinking. Puff pastry is made from butter that is incorporated into flour in layers. It's turned over several times by folding it like a letter. Then it's rolled out, turned again, and refrigerated between turns.
Phyllo dough is a very thin layer in itself.
You usually pile up between three and five layers, with butter and sugar or flour in between. It's mainly a difference in how the layers are achieved. It's very important when using phyllo dough to use a damp towel to cover it, as it will become brittle and hard to use if it dries out at all. With puff pastry, you want to prevent it getting to room temperature, as the butter will melt. You can make it this week, then wrap it well with plastic wrap or foil.