1. Syntax Differences: JavaScript: JavaScript uses curly braces {} and semicolons ; to define blocks of code and terminate statements. PHP: PHP uses semicolons ; to terminate statements and uses curly braces {} for control structures like loops and conditional statements, but not for defining blocks of code. Python: Python does not use curly braces {} or semicolons ; to define blocks of code or terminate statements. It uses indentation to define blocks of code.

2. Type System Differences: JavaScript: JavaScript has a weak dynamic type system, meaning variables can hold values of any type and their types can change at runtime. PHP: PHP has a weak dynamic type system similar to JavaScript, where variables can hold values of any type and their types can change at runtime. Python: Python has a strong dynamic type system, meaning variables are bound to specific types and their types cannot change at runtime.

3. Variable Declaration Differences: JavaScript: In JavaScript, variables can be declared using the var, let, or const keyword. The var keyword has function scope and the let and const keywords have block scope. PHP: In PHP, variables are declared using the $ sign followed by the variable name. No specific keywords are required for variable declaration. Python: In Python, variables can be assigned a value without any explicit declaration. They are created when first assigned a value.

4. Function Definition Differences: JavaScript: In JavaScript, functions can be defined using the function keyword followed by the function name and a set of parentheses. Parameters are specified within the parentheses. PHP: In PHP, functions can be defined using the function keyword followed by the function name and a set of parentheses. Parameters are also specified within the parentheses. Python: In Python, functions can be defined using the def keyword followed by the function name and a set of parentheses. Parameters are specified within the parentheses.

5. Object-oriented Programming Differences: JavaScript: JavaScript supports object-oriented programming and uses prototypal inheritance. Objects can be created with the new keyword and prototype-based inheritance is used to create object hierarchies. PHP: PHP supports object-oriented programming and uses class-based inheritance. Objects can be created using the new keyword and classes can be defined with the class keyword. Python: Python supports object-oriented programming and uses class-based inheritance. Objects can be created using the new keyword and classes can be defined with the class keyword.

6. Web Development Differences: JavaScript: JavaScript is primarily used for client-side web development to add interactivity and dynamic content to websites. It can be embedded into HTML pages or included as separate files. PHP: PHP is mainly used for server-side web development, where it is embedded within HTML or used to generate HTML dynamically. It can also be used for command-line scripting. Python: Python can be used for both server-side and client-side web development. It is often used for server-side web development using frameworks like Django or Flask. It can also be used for scripting and automation.

In Summary, JavaScript, PHP, and Python differ in terms of syntax, type system, variable declaration, function definition, object-oriented programming approach, and their usage in web development.