Don't want to pay more TDS ? Which tax regime should you choose?

The month of April is very important for the salaried class in terms of tax planning. In this month you have to inform your company about the tax regime of your choice. On the basis of this, TDS is deducted from your salary. What is the difference between tax regime and old tax regime? Which regime is suitable for which type of salaried class? How to calculate tax before choosing the regime?