There is little difference in meaning. There is a slight difference in perspective.
Tomorrow it will be ten years since we were married.
This sentence has a slightly forward-looking perspective, as if I'm thinking about the future with my wife.
Tomorrow it will have been ten years since we were married.
Again, similar meaning, but the use of the perfect has a slightly backward-looking perspective, as if I'm considering all that time we spent together.
Neither is more correct than the other, and neither is in any way negative (unless I say it in a way that seems sarcastic or disparaging). These are just two ways to say the same thing but with a subtle difference in nuance.
Connective prepositions before, after, when, while, as soon as, etc. may be added to a clause to express that a second activity occurs earlier than, later than or at the same time as the activity in the main clause.
If the verb in the main clause is present tense, the verb in clause following the preposition is also present.
After we finish our homework, we go for a walk. (later then, as we
usually do)
Connective prepositions may also be added to a clause with a future tense verb expression such as will or (be) going to. In this case, the verb in the clause following the connective preposition does not change tense. It remains in present tense form.
After we finish our homework, we'll go for a walk. (later then, today)
So, the correct choice will be
It will be delivered after it is inspected. (first it will be inspected then delivered)
The difference between variants A, B, and C is that only variant A is grammatically correct.
Best Answer
The first sentence uses a simple future. It means that by 2025, they begin to build, start to build a settlement. In the second sentence, however, a future perfect is used, meaning that by 2025, the process of building that settlement will have been completed.
So, simply put: In the first sentence, the settlement will not yet be there by 2025, but in the second sentence, the settlement will be completely finished and ready by 2025.