What's the difference between legacy and current service fabric installation mode?

Hello, @Qianqian Zu ! Thank you for being patient as we reached out to the Service Fabric team. We are still waiting for a response but hopefully the answer from the documentation will address your question. If not, please let us know in the comments and we'd be happy to investigate this further.

What is the difference between a standalone cluster and development environment for Azure Service Fabric?

Azure Service Fabric offers the ability to create a standalone cluster which offers additional flexibility in hosting options in addition to Azure clusters. When creating a standalone cluster running on Windows Server, you will still use the PowerShell command which references the config file path:

https://video2.skills-academy.com/en-us/azure/service-fabric/service-fabric-cluster-creation-for-windows-server#download-the-service-fabric-for-windows-server-package

.\CreateServiceFabricCluster.ps1 -ClusterConfigFilePath .\ClusterConfig.Unsecure.DevCluster.json -AcceptEULA

It's also possible to set up a development environment which will allow you to build and run Azure Service Fabric applications on a Windows development machine. This is installed using an .exe like you described (example: MicrosoftServiceFabric.9.1.1583.9590.exe). This process allows you to use Visual Studio to create Service Fabric applications, add services, or package, register, and deploy applications in your local development cluster.

https://video2.skills-academy.com/en-us/azure/service-fabric/service-fabric-get-started

Here are instructions on how to manage your cluster using Visual studio and Cloud Explorer:
https://video2.skills-academy.com/en-us/azure/service-fabric/service-fabric-manage-application-in-visual-studio