You have to be more specific, which model and which telco, because also operators sometimes change the phone (install operator-specific software and remove additional languages to gain space to install own software).
Basically there's always difference. For example my last 2 phones was delivered for central european market, it means central european languages was installed. Most phones sold in Asia have asian languages and english installed, you can switch it to english, but sometimes the keyboard shows additional asian characters. This can be fixed by installing some new keyboard.
If you buy some normal phone (like HTC, Samsung, ...), it can be flashed to european or custom ROM (for example if you need additional central or east european languages, which are not present in asian version), if you buy some "noname" phone, it mostly offers just major languages (many asian languages, english, maybe also german or spanish).