API Automation: @QueryParam vs @PathParam

@QueryParam is used to access key/value pairs in the query string of the URL (the part after the ?).

@PathParam is used to match a part of the URL as a parameter.

Let's see how
If there is a scenario to retrieve a record based on id, for example you need to get the details of the employee whose id is 15, then you can have resource with @PathParam.

GET /employee/{id}

If there is a scenario where you need to get the details of all employees but only 10 at a time, you may use query param

GET /employee?start=1&size=10

This says that starting employee id 1 get ten records.

Example 2:
If you have a url with three segments, each one passing different parameters to search for a car via make, model and color:

www.example.com/search/honda/civic/blue

This is a very pretty url and more easily remembered by the end user, but now your kind of stuck with this structure. Say you want to make it so that in the search the user could search for ALL blue cars, or ALL Honda Civics? A query parameter solves this because it give a key value pair. So you could pass:

www.example.com/search?color=blue
www.example.com/search?make=civic