Robot Framework vs JUnit comparison of testing frameworks
What are the differences between Robot Framework and JUnit?

Robot Framework

https://robotframework.org/

JUnit

https://junit.org/junit5/
Programming language

Python

Java

Category

Acceptance Testing

Unit Testing, Regression Testing

General info

Robot is a Python framework used for acceptance/functional testing

Robot is an automated test framework which has a simple plain text syntax and can be extended easily with Python or Java libraries. It can run on the .net-based IronPython and on Jython which is Java based.

JUnit is an open source Unit testing framework for java

JUnit is useful for developers to write and run repeatable tests. JUnit has been crucial in the development of test driven development and is partof the xUnit family of unit testing frameworks
xUnit
Set of frameworks originating from SUnit (Smalltalk's testing framework). They share similar structure and functionality.

No

Yes

It is an instance of the xUnit architecture for unit testing frameworks.
Client-side
Allows testing code execution on the client, such as a web browser

Yes

Robot has a rich library and can also be easily integrated with Selenium for browser automation to test front-end components

Yes

You can test front-end components such as individual classes and functions that create the front-end
Server-side
Allows testing the bahovior of a server-side code

Yes

Robot can be used for back-end tests as well

Yes

You can test classes and functions that compose the back-end such as database connections and so on
Fixtures
Allows defining a fixed, specific states of data (fixtures) that are test-local. This ensures specific environment for a single test

There is no inbuilt way to work with fixtures in Robot however it can integrate with unittest and use fixtures that way

Yes

JUnit contains a setUp() method, which runs before every test invocation and a tearDown() method, which runs after every test method.
Group fixtures
Allows defining a fixed, specific states of data for a group of tests (group-fixtures). This ensures specific environment for a given group of tests.

By integrating with unittest

Yes

You can use setUp() and tearDown() inbuilt functions as group fixtures.
Generators
Supports data generators for tests. Data generators generate input data for test. The test is then run for each input data produced in this way.

Yes

Robot has a library called the Robot Framework Faker library. It contains 147 keywords used for generating random test data

You can use JUnit-quickcheck to generate test data
Licence
Licence type governing the use and redistribution of the software

Apache License 2.0

Mocks
Mocks are objects that simulate the behavior of real objects. Using mocks allows testing some part of the code in isolation (with other parts mocked when needed)

Yes

Robot can access Python's mock library for mocking

JUnit does not support mocking internally but you can use a mock framework like Mockito to generate mock objects.
Grouping
Allows organizing tests in groups

Yes

One can create a test suite with Robot

Yes

In JUnit you can create a test suite that bundles a few unit test cases and runs them together. You use both @RunWith and @Suite annotation are used to run the suite test.
Other
Other useful information about the testing framework