Basically coding can be done in two forms, at the server end or at the client end. Language or technology does not define whether you are writing client side or server side code. Server side coding involves server for its processing. On the other hand, client-side coding requires browsers to run the scripts on the client machine like Iphone, Andriod, PC etc. but does not interact with the server while processing the client-side scripts.
This is explained in detail with proper examples in our video tutorial Client Side vs Server Side Code What is the Difference | 0010-00. Snapshot of our video session is shown below:
Now-a-days we can write server side code also in angular. For this new library called as NestJS is coming up which will enable you to apply your angular principles to write server side coding as well. It will make developers life easier; they need not to know about ExpressJS etc. for server side coding.