Yule log cake - help with filling

I’m making a yule log cake based on a recipe I found online. The recipe for the filling part is basically chocolate whipped cream, but I don’t want it to be chocolatey. I want just plain whipped cream for the filling, but I’m not sure it’ll hold up for long. I’m new to this, please advise!

The cake is for Christmas day. So far I’ve made the cake and rolled it up. When should I do the rest of the assembly to be sure it’ll keep ok till Christmas dinner?

The filling for that is a basic mousse. Whipped cream will be absorbed by the cake. You could make the mousse with white chocolate. You could get away with whipped cream if you assembled it the day you serve it. Otherwise you could make it a day or two ahead.

One more question, then - what makes a mousse different from a whipped cream? In this specific recipe all I’m adding to the whipped cream is melted chocolate and more cream.