"I am already here."
Translation:Я вже тут.
Is there any difference between "вже" and "уже"? Are they interchangeable? If not, what would be some examples of their correct usage?
They are interchangeable.
Most (all?) words in Ukr that start with в+consonant have their у+consonant counterpart (for the sake of euphony): вчитель-учитель, вже-уже, вночі-уночі, впасти-упасти.
You should try to avoid congestion of consonants and use у-versions after a consonant. But this rule is sometimes neglected and because of that в-versions of some words became much more common
Vinnfred is absolutely right. Usually, one trying to avoid match three and more of consonants consecutive.
Мій кіт Уродли́вий (вродли́вий/га́рний).
Порт і капітан (instead поРТ Та капітан [three of consonants] or поРТ Й Капітан [four of consonants]).