What is ECMAScript?

Question

What is ECMAScript? Why is it in the JavaScript course? What are the similarities between ECMAScript and JavaScript? And which one is harder to learn, in your opinion?

Answer 1

Javascript is the web superset of ECMAScript (ES)... ie: same with web api specific addition (DOM, canvas, and so on...)

ES is the blueprint, and JS, nodeJS, or even ActionScript (Flash) are implementation of ES.
They share the core languages syntaxic rules, but would differ on provided api ;)

Answer 2

You already found it in the Javascript course and all your questions are answered there right in the introduction.