Dear Friend,

The Question you asked, is very sensible and genuine. This is the quest that many guys might have in their mind.
Introducing Kotlin as Professional approved Language for android Application was a obvious step, but after some time flutter is introduced, and all of us, including me thought perhaps Google realized that Kotlin introduction as a Approved language is mistake, and via flutter they are correcting the mistake.

Personally i thought , it will ruin the Kotlin perhaps.
But Later on when I learnt Flutter and its flexibility, simplicity and freedom to use native codes too is awesome and then I realised that Google introduced Kotlin and Flutter for different purposes.

Kotlin is a programming language that can be used to build Android apps, as well as apps for other platforms. Google officially announced first-class support for Kotlin on Android in May 2017, and since then, Kotlin has become a very popular language for Android development. It is designed to be more concise and expressive than Java, and it also helps developers avoid common programming mistakes.

Flutter, on the other hand, is a mobile app development framework that allows developers to build natively compiled apps for mobile, web, and desktop from a single codebase. It uses the Dart programming language, which was also developed by Google. Flutter was designed to make it easy for developers to build high-quality, visually attractive apps that can run smoothly on a variety of platforms.

In summary, Kotlin is a programming language that is primarily used for Android development, while Flutter is a framework for building cross-platform mobile apps.

we have made many apps in java/kotlin and flutter too.

In fact our official app is totally flutter based and you can found it on google play store by click here.

In short these are the tool, we can use whichever we want to use depending upon our requirements , interests etc.