Adhutsul,
Both villages have the same name in Ukrainian: Гаврилівці, you just provided different English spellings of the same name. The towns are located about 100km from each other:
https://goo.gl/maps/yG4yS. One in Chernivtsi province, another in Hmelnytskyi Province.
Yes, you should send letters in Ukrainian.
1. Village council address for Havrylivtsi in Chernivtsi Province (just copy and paste on the envelope):
Сільська Рада
вул. Головна, 59
с. Іванківці,
Кіцманський р-н
Чернівецька обл
Ukraine 59320
2. Village council address for Havrylivtsi in Khmelnytska Province:
Сільська Рада
с.Руда
Кам’янець-Подільський р-н,
Хмельницька обл.
Ukraine 32366
______________________________________________
Things will be much easier if you just call the village councils to make inquires: if you like I can help. Fee free to contact me via west.ukraine.tours at gmail.com.
Regards,
Andriy
West Ukraine Tours