Opera Mobile 10, Opera Mini 5.x and Opera Mini 4.2
Above is the list from opera.com for free mobile browsers apps, the differences between those list is technical specifications on each browser applications, Opera Mobile 10, Opera Mini 5.x and Opera Mini 4.2. According to it’s official site (opera.c0m), Opera Mobile 10 is the best mobile browser application which have a lot of features that built in it. Such like support for full rendering engine on device and Adobe Flash support, that you can’t found on the Opera Mini 5.x and Opera Mini 4.2. But, Adobe Flash support that built in Opera Mini 10 is only for Windows Mobile only.
Opera Mobile 10 support platform
S60, Windows Mobile, Android, Maemo (labs edition*) with 40 languages supported in user interface
Opera Mini 5.x support platform
Java phones, Windows Mobile, Android, S60, Blackberry, iPhone with 96 languages supported in user interface.
Opera Mini 4.2 support platform
Java phones, Blackberry with 96 languages supported in user interface.
Comparison between Opera Mobile 10 and Opera Mini 5.x, is just only the full rendering engine on device and Adobe Flash support that built in Opera Mobile 10 . Meanwhile Opera Mini 4.2 is not support for Next generation mobile UI, Tabs, Full rendering engine on device, Adobe Flash support, Optimized UI for touchscreen devices, Speed Dial, Visual tabs, Kinetic scrolling, Download manager, Predictive text input, Password manager, Accelerometer support (for switch to landscape mode), Virtual keyboard (Touchscreen only) and Smooth animations in user interface.
Finally, if you want to download opera mobile browser application straight from opera.com you can go to opera site, and choose the correct specifications for your mobile phones.