Differences between requires_new and nested propagation in Spring transactions
PROPAGATION_REQUIRES_NEW : uses a completely independent transaction for each affected transaction scope. In that case, the underlying physical transactions are different and hence can commit or roll back independently, with an outer transaction not affected by an inner transaction's rollback status.
PROPAGATION_NESTED : uses a single physical transaction with multiple savepoints that it can roll back to. Such partial rollbacks allow an inner transaction scope to trigger a rollback for its scope, with the outer transaction being able to continue the physical transaction despite some operations having been rolled back. This setting is typically mapped onto JDBC savepoints, so will only work with JDBC resource transactions.
check spring documentation
See this link: PROPAGATION_NESTED versus PROPAGATION_REQUIRES_NEW? Juergen Hoeller explain it very well. -- the Spring Source Forum is completely offline sice February 28, 2019, but you can read the relevant part of the article in the quote below
PROPAGATION_REQUIRES_NEW starts a new, independent "inner" transaction for the given scope. This transaction will be committed or rolled back completely independent from the outer transaction, having its own isolation scope, its own set of locks, etc. The outer transaction will get suspended at the beginning of the inner one, and resumed once the inner one has completed. ...
PROPAGATION_NESTED on the other hand starts a "nested" transaction, which is a true subtransaction of the existing one. What will happen is that a savepoint will be taken at the start of the nested transaction. Íf the nested transaction fails, we will roll back to that savepoint. The nested transaction is part of of the outer transaction, so it will only be committed at the end of of the outer transaction. ...