[Grammar] By 10 o'clock I will arrive home.

[beachboy]

What's the difference between "By 10 o'clock I'll arrive home" and "By 10 o'clock I will have arrived home"? When is it preferable to use one instead of the other? And also, is there another meaning for the preposition "by" in the first sentence, I mean, can it mean "around"?

 

[bhaisahab]

'I'm going out now, I'll be home by 10 o'clock.' Natural in all cases.

 

[beachboy]

'I'm going out now, I'll be home by 10 o'clock.' Natural in all cases.

And what's the difference between "By 10 o'clock I'll arrive home" and "By 10 o'clock I will have arrived home"?

 

[Raymott]

A: You can't watch the TV news at 10 o'clock. You're going out tonight.
B: Yes, but I will have arrived back home by 10.

Like all perfect tenses, the determinant of the tense often occurs outside the sentence. (Not that the perfect is mandatory here.)
Doesn't Portuguese have a future perfect tense?

 

[beachboy]

A: You can't watch the TV news at 10 o'clock. You're going out tonight.
B: Yes, but I will have arrived back home by 10."

Like all perfect tenses, the determinant of the tense often occurs outside the sentence.
Doesn't Portuguese have a future perfect tense?

It does. But we can easily substitute it for the future with will. The two sentences mean the same in my language. That's why I'm still asking about the difference in English.

 

[Raymott]

The difference in English is that the simple future looks forward. "I will arrive home (in the future) by 10pm."
The future perfect looks back from the future. At 10pm, I will be able to say, "I have arrived home."
It's a matter of perspective. The difference in meaning in this case is simply where the emphasis is placed.

PS: This might help:
https://en.wikipedia.org/wiki/Future_perfect