Can you explain the difference between Abstract Factory and Builder patterns with examples?

Short answer: Abstract Factory: Provides an interface for creating families of related objects without specifying concrete classes.

Example code

Creating UI components for different OS (Windows, Mac). Builder: Focuses on step-by-step construction of a complex object, allowing different representations. Example: Building a complex House with various parts (walls, doors, roof). Summary: Abstract Factory is about families of products, Builder is about complex construction process.

Real-world example (ShopNest)

ShopNest payment fees use Strategy: IFeeCalculator with UPI/Card implementations chosen at runtime.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.