CGST, SGST and IGST
The three parts GST is charged as: central and state halves on a sale within a state, integrated tax on a sale between states.
On a sale within one state, GST is charged in two equal halves: CGST, which goes to the centre, and SGST (or UTGST in a union territory), which goes to the state. On a sale between states, the same total is charged as one tax, IGST.
The customer pays the same amount either way. What changes is how the invoice shows it and how the credit flows — which is why the place of supply has to be right.
Learn it in a lesson
See also: Place of supply, Input tax credit (ITC)