1. Difference between var, let, and const: var is function-scoped and can be redeclared or updated, let is block-scoped and can be updated but not redeclared, const is block-scoped and cannot be updated or redeclared.

2. Difference between map(), forEach(), and filter(): map() returns a new array after transforming elements, forEach() loops through elements without returning a new array, filter() returns a new array with elements that pass a condition.

3. Arrow functions in ES6: shorter syntax for functions like const add = (a, b) => a + b; and this behaves differently than in regular functions.

4. Destructuring assignment in ES6: allows easy extraction of values from arrays or objects, e.g., const [a, b] = [1, 2]; const {name, age} = {name:"Alice", age:25};.

5. Template literals in ES6: use backticks ` to include variables and multi-line strings, e.g., `Hello, ${name}!`; cleaner than string concatenation and supports multi-line easily.