In case of supply of exempt goods or when tax is paid under Composition Scheme, is the registered person required to issue a tax invoice? How a bill of supply is different from a tax invoice?

No. In such cases, the registered person shall issue
a Bill of Supply and not a tax invoice. The bill of supply is
different from a tax invoice both in name and details
contained. While most of the details to be provided
in a bill of supply are similar to tax invoice, the bill of
supply does not contain the rate of tax and the amount of tax
charged as the same cannot be collected.