iOS 4.2.1 vs iOS 4.3.2
When looking at the differences between iOS 4.2.1 and iOS 4.3.2, we should take in consideration that there have been a number of patches that appeared in between iOS 4.2.1 and iOS 4.3.2. To be exact, these are the patches after 4.2.1: 4.2.5, 4.2.6, 4.2.7, 4.2.8, 4.2.9, 4.2.10, 4.3, 4.3.1, and finally 4.3.2. You cannot get iOS 4.3.2 without applying the 8 other patches. So the differences between iOS 4.3.2 and iOS 4.2.1 may not come from the last patch alone but from the accumulated patches.
One of the changes that you will not find in iOS 4.2.1 is support for CDMA networks. At the outset, until version iOS 4.2.1, Apple only released iPhones for the GSM networks; leaving subscribers under CDMA networks wanting. With the CDMA version of the iPhone 4, they get their piece of the pie. The newer iPad 2 was also released after iOS 4.2.1, so you will not see an iPad 2 with iOS 4.2.1 but iOS 4.3.2 is common with the iPad 2.
When it comes to new features, there is a couple that stands out. The first is how Apple has introduced the ability for third party apps to use Airplay. Airplay allows the app to stream audio, video and photos to devices that are capable of receiving content via Airplay. This lets you watch movies and photos wirelessly on your TV, or stream music to Airplay compatible speakers. Another improvement in iOS 4.3.2 is the Nitro Javascript engine used in Safari. This allows Safari to render Javascript pages quicker and with fewer resources.
Also, there has been numerous tweaks and fixes introduced between iOS 4.3.2 and iOS 4.2.1 that improve performance and address bugs that were found. These are too numerous to list and basically achieve the same thing. It is easy to conclude that iOS 4.3.2 is simply a better version of the iOS operating system than iOS 4.2.1.
Summary:
1.iOS 4.3.2 also includes a number of patches that appeared after iOS 4.2.1
2.iOS 4.3.2 supports CDMA networks while iOS 4.2.1 doesn’t
3.iOS 4.3.2 is used in the iPad 2 while iOS 4.2.1 isn’t
4.iOS 4.3.2 allows third party apps to use Airplay while iOS 4.2.1 doesn’t
5.iOS 4.3.2 has a new Javascript engine that iOS 4.2.1 doesn’t have
6.iOS 4.3.2 has a great number of tweaks and fixes that improve performance over iOS 4.2.1