"Sie" instead of "sie" is only written in letters. You only capitalise a formal "Sie" and informal "Du" in letters (which most Germans -like me- hardly do). In a book you would commonly read "Irgendwie sind sie anders." e.g. as part of a dialogue.
So the bottom line is, that the translation "Somehow you are different." is absolutely plausible.
Not quite. Unlike "du", "Sie" in the sense of "you" is capitalised everywhere, no matter if it's a letter, direct speech, an advertisement or some other text.
And you don't have to take my word for it, BTW ;-) https://www.duden.de/sprachwissen/sprachratgeber/Gross-oder-Kleinschreibung-von-sieSie
The fact that many people make spelling errors doesn't make these errors right. Similarly, many native English speakers write things like: "I should of come" (instead of: "I should have come") or confuse the spellings for "ei" and "ie". Still wrong, even if many people use these spellings.
It would be a good translation for the English sentence (except it's “verschieden”, no final -e) , however it would mean something else than the original German sentence:
“sie sind verschieden” = “they are different (from one another)”
“sie sind anders” = “they are different (from something else assumed to be similar)”
In other words: “verschieden” = internal difference; “anders” = external difference.
In this sentence, "sie" doesn't mean "you [formal]" because it's not written with an upper-case "s", i.e. it's "sie" and not "Sie" (see my previous explanation below).
Also, "anders" actually means "different", and not "changed". While there are some contexts in which "different" and "changed" can be used as synonyms, that's not necessarily the case – for example, the sentence could just mean that they are different from somebody else.
It sounds like a question to the English ear, but to the German ear what matters is not the position of the subject relative to the verb, but the absolute position of the verb in the clause, namely: in declarative main clauses the verb has to be in second position always; if the first position is occupied by anything else but the subject, then the subject must go after the verb. In yes-or-no questions, the verb comes first, before anything else. The corresponding question to this statement would for example be: ‘sind sie irgendwie anders?’.