I think these following sentences are equivalent in terms of meaning.
I'd like to ask if there is subtle difference in terms of meaning?
Which one is more common?Can we say one or other is more formal?
You are smiling in all your photos.Your trip has to have been fun.
You are smiling in all your photos.Your trip must have been fun.
And how about this sentence.Is it used/said when we talk about a trip went on many years ago?
You are smiling in all your photos. Your trip had to have been fun.