What shapes the cost of living
Housing is the largest and most variable cost, but transport, food, utilities and childcare matter too. A city with cheaper rent but no public transport can be more expensive once you need a car, so always compare totals rather than single line items.
Gross versus net income
Taxes and social contributions change take-home pay dramatically between countries. Comparing gross salaries hides this. Convert both to net income in a common currency before you judge whether one place is really better off.
Quality of life is part of the equation
Cost is only half the story. Climate, safety, healthcare, language and proximity to family all shape whether a place is right. A slightly higher cost in a place you enjoy can easily be worth it.