Blazor uses technologies like WebAssembly and SignalR. WebAssembly allows Mono Runtime to execute inside browser. It is like running .NET runtime environment inside browser. Other frameworks use Typescript or JavaScript.

Blazor uses webAssembly (WASM) for client application rather than JavaScript. For server side app communication it uses SignalR . It uses C# to build interactive webUI components. Both Client and server side code is built using c# and hence can be shared. It can be used in all scenarios you would use AngularJS , ReactJS , Vue.JS etc. You can develop webapp , clientapp and even desktop apps*. As a future scope you can build mobile native apps using blazor and xamarin.