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In JavaScript, data is divided into primitive types and objects.

Primitive types:

• String: Sequence of characters. Immutable.
• Number: Numbers, including integers and floating-point, as well as Infinity, -Infinity, and NaN.
• Boolean: Logical value (true or false).
• Null: Special value representing the absence of an object.
• Undefined: The value of a variable that has not been assigned a value.
• Symbol: A unique and immutable primitive type used as identifiers for object properties.
• BigInt: Integers of arbitrary length.

Objects:

• Object: A collection of key-value pairs. Mutable. Examples: arrays, functions, regular expressions, dates.

Main differences:

1. Mutability: Primitive types are immutable, meaning their values cannot be changed directly. Attempting to change creates a new copy. Objects are mutable, and their properties can be added, removed, or changed.
2. Pass by value/reference: Primitive types are passed by value (copied). Objects are passed by reference (a reference to the memory location where the object is stored is copied).
3. Comparison: Primitive types are compared by value. Objects are compared by reference (two variables refer to the same object in memory).

// Examples
let str1 = "hello";
let str2 = str1; // str2 gets a copy of str1's value
str1 = "world"; // A new string "world" is created for str1
console.log(str2); // "hello" - str2 did not change

let obj1 = { name: "Alice" };
let obj2 = obj1; // obj2 references the same object as obj1
obj1.name = "Bob"; // The object's property is changed, both variables point to it
console.log(obj2.name); // "Bob" - obj2 has changed

let num1 = 10;
let num2 = 10;
console.log(num1 === num2); // true - values are equal

let objA = { value: 1 };
let objB = { value: 1 };
console.log(objA === objB); // false - references are compared (pointing to different objects, even if contents are same)

Comparison table:

Feature	Primitive types	Objects
Mutability	Immutable	Mutable
Passing	By value	By reference
Comparison	By value	By reference
Storage	Directly in variable	Reference to memory location
Data types	String, Number, Boolean, Null, Undefined, Symbol, BigInt	Objects (including arrays, functions, etc.)