PHPUnit vs Cucumber comparison of testing frameworks
What are the differences between PHPUnit and Cucumber?

	PHPUnit https://phpunit.de/	Cucumber https://github.com/cucumber/cucumber-ruby
Programming language	PHP	Ruby
Category	Unit Testing	Acceptance Testing
General info	PHPUnit is a unit testing framework for the PHP programming language PHPUnit is a programmer-oriented testing framework and is an instance of the xUnit architecture for unit testing frameworks.	An automation tool for Behavior-Driven Development The specifications are written in plain texts, which allows them to be easily understandable for all stakeholders. Cucumber Framework also supports languages beyond Ruby e.g. Java, JavaScript and Scala.
xUnit Set of frameworks originating from SUnit (Smalltalk's testing framework). They share similar structure and functionality.	Yes It's an instance of the xUnit architecture for unit testing frameworks	No
Client-side Allows testing code execution on the client, such as a web browser	Yes It can perform Unit tests and can test various front-end components and behaviours	Yes You can test the front-end part like the GUI using cucumber and selenium, they integrate well to test your front-end.
Server-side Allows testing the bahovior of a server-side code	Yes By performing unit tests on singular back-end components	Yes You can test back-end components such as APIs using rest & soap clients, and databases using whatever client libraries were provided by the libraries that existed in those stacks
Fixtures Allows defining a fixed, specific states of data (fixtures) that are test-local. This ensures specific environment for a single test	Yes By use of a setup code. The setup code consists of two Important template functions, the 'setUp()' function (called to create the objects to be tested) and 'tearDown()' function (called to cleanup the objects which you tested)
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.	Yes It does support group fixtures	Yes Using the cucumber extension aruba you can create fixures in two steps: 1.Create a fixtures-directory; 2.Create fixture files in this directory
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.	N/A	Yes You can group your fixtures inside your fixtures directories
Licence Licence type governing the use and redistribution of the software	Creative Commons Attribution 3.0 Unported License	MIT License
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 One of its main features is that PHPUnit comes with out of the box support for Mock objects	Yes By using all of RSpec’s supported mocking frameworks (RSpec, Mocha, RR, Flexmock)
Grouping Allows organizing tests in groups	Yes It allows grouping of tests and by using the @group annotation one can tag a test to belong to one or more groups	Yes Cucumber allows the use of tag Cucumber feature files or individual tests to group tests. Then, you can pass a Cucumber tagged expression at test execution that specifies the tag (grouped) tests to run. https://www.toolsqa.com/cucumber/cucumber-tags/
Other Other useful information about the testing framework