In the Android Studio toolbar, we have 2 buttons:
What'sthedifferencebetweenthem?Andwhentouseoneortheother?
Update
DoestheIDEidentifytheneedtousethe"Run App"? That is, when a change is made that the "Apply changes" will not apply, only the "Run App" button will be active?
Apply Changes: Send only the changed part of the code, and does not create a new APK and in some cases restart some activity .
Run App: In this case it restarts the application, updates the manifest , and sends another APK .
Source: run app vs apply changes android studio 2.3
Update
Run App
To compile and run your application, click Run. Android Studio compiles your application with Gradle, prompts you to select a deployment target (an emulator or device connected) and deploy your application on it. You can customize some of these default behavior, such as selecting a deployment, by changing the run configuration.
Apply Changes
After you deploy an application, a small yellow ray icon will be displayed on the Run button (or the Debug button), indicating that Instant Run ready to send updates the next time you click the button. Instead of compiling a new APK, it sends only these new changes, and in some cases, the application does not even need to be restarted and immediately shows the effect of code changes.
More information from the IDE's own website: Compile and run your application
The most up-to-date English site: Build and Run Your App
