In programming, frameworks allow programmers to concentrate on the actual tasks they are faced with rather than to waste their time reinventing the wheel. Usually, frameworks are shipped with a set of predefined functions and classes. When using Spring (Java) or Symfony (PHP) for example, programmers do not need to think about things such as persistence, routing and session management too much because the work is done by standardized framework components.
platform, on the other hand, provides both the hardware and the software tools needed to run an application – be it a standalone program or one which has been built on top of a framework. Mostly, it comes in the flavor of Platform-as-a-Service (PaaS), meaning that the code-base of the platform software itself is not distributed or licensed. Like .NET platform or Windows platform or various cloud-based Platform-as-a-service solutions (like Heruko)
Nodejs, JAVA, .NET are examples of platforms or development platforms. This becomes the core of web application.
You work on a platform. You use a framework.