Q:

How is Testim.io different from Selenium? 

Testim.io is an automated testing platform.  How is it different from Selenium? 

A:

Testim.io is a SaaS applying machine learning to test automation.  
Usage: You use testim's plugin to record test cases or bugs (& submit to Trello/JIRA).  You can then edit and add javascript or image validation to your tests, and run them via testim's site or via CLI and your CI/CD cloud to execute your tests. 
Machine Learning: When you record tests, testim uses machine learning weighting rather than individual CSS Selectors or XPath to identify DOM elements to test.  When you execute tests, the tests rebalance weighting, so you don't have to continually fix your ! @#$% tests because you (or React.js) changed the name of the selector or XPath element.