You cannot tell from the title screens of any of the games. You're probably thinking of the title screen's regional variation from Japanese to English.
The best way to tell is the number embossed on the right side of the label. 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 damaged 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 next easiest way I can tell, which should work for both games, is to enter a Pokémon Center, go upstairs, and talk to the third lady (for mixing records). On Version 1.0, she will refer to this 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