Trame is the evolution of ParaView Web. VTK/ParaView Web is a set of pieces that allow you to do interactive remote/local rendering using your web stack of choice. When using VTK/ParaView Web, you can develop your server in Python and enable efficient client/server communication over websocket for doing RPC and publish/subscribe. For the client side you are responsible of your stack and development.
With trame, you write a Python script that is both the server logic and client presentation and connect the two effortlessly. This allow you to create focused applications faster while reducing the maintenance cost. Trame is really the evolution of VTK/ParaView Web that let you do more with less.