You cannot tell from the title screens. The international versions updated the text but they are the same across all revisions.
The best way to tell is the number embossed on the right side of the label (on an authentic cartridge). If this number is just two digits, it is Version 1.0. If it has an 'A', it is Version 1.1. If it has a 'B', it is Version 1.2.
(Click each version to see its respective reference image . . . I couldn't find a picture of Revision B)
If you have a missing or illegible label, you will have to scout for in-game signs.
If you’re playing Ruby, you can quickly tell if you have Mawile in your Pokédex. Mawile’s ‘Dex entry misspells its name as MAWHILE in 1.0. Although this won’t help you distinguish 1.1 from 1.2.
The easiest way I can tell, which works for both games: Enter a Pokémon Center, go upstairs, and talk to the third lady (for mixing records). On Version 1.0, she will refer to this place as the “Record Center”. On Version 1.1, she will call it the “Record Corner”.
Other changes have been documented on this page.
As far as I can tell, the only change made from 1.1 to 1.2 is the fix of the Berry Glitch. Which is obviously more tedious to test for.
(Note this is in reference to English versions of the game. Other versions apparently only got a 1.1 update for the Berry Glitch)
Sources: Chieftan20's authenticity guide, Glitch City archive, Reddit, TCRF