Most apply to both countries (and Mexico and other countries sometimes) but the only way to know for sure is probably to try it. Perhaps a web-search for the number in question (or the company) will turn up applicability to which country...
I can imagine how frustrating it is to be billed for a service you have not used. 😞
The Roam Like Home charge will apply if you are travelling outside of Canada to an applicable destination and you use any data, make an outgoing SMS or if you initiate or answer a phone call.
Do you recall using any data on your device? Many apps use push notifications which will use data in the background even if you aren't directly using the device. Feel free to contact us via any of the options listed here: rogers.com/contactus. You can utilize the Live Chat or Social Media Support options if you are unable to call while overseas.