It is re-issue of OCI.

Paperwork gets sent from INdia.
You have to cancel old OCI and get new OCI card as well as new sticker in new passport.
Process can take one to two months in addition to hassles of dealing with Indian Consulate (something I thought LIFE LONG visa meant never again)

But more critically, you lose ability to travel to India at moment's notice because as soon as you get new US passport, old OCI is invalid.

With 10 year visa, you can still travel with old passport and new passport