Here is the RBA's explanation. NOV appears to fall into category two.

SpeechThe Future of Payments: Cryptocurrencies, Stablecoins or Central Bank Digital Currencies?

Tony Richards^[*]
Head of Payments Policy

Address to the Australian Corporate Treasury Association
Online – 18 November 2021

• Webcast

Audio Download 261KB

https://www.rba.gov.au/speeches/2021/sp-so-2021-11-18.html

Stablecoins

The second group of new digital assets, so-called ‘stablecoins’, are a type of crypto-asset or token specifically designed to minimise price volatility against a widely used unit of account (such as the US dollar) or a common store of value (such as gold). This is to make them more money-like and attractive as a store of value or method of payment. One way their promoters seek to maintain a stable value is by holding assets that back the coins on issue. However, these backing arrangements to date have had varying degrees of credibility, especially in the case of Tether, the largest stablecoin by market capitalisation, which was recently fined US$41 million by the US Commodity Futures Trading Commission for misleading statements regarding its assets being fully backed.

Within this group, it may be useful to distinguish between three possible broad types of stablecoins:

• The first category includes essentially all the existing stablecoins, such as Tether, USD Coin and Binance USD. These can be thought of as a bridge between fiat currency and cryptocurrency. They are being used both for payment or settlement for transactions involving cryptocurrencies or tokenised assets, and also as a store of value by people who may have traded in cryptocurrency and wish to then switch to a fiat currency claim but without leaving the distributed-ledger technology (DLT) ecosystem.^[3] They are typically issued onto public blockchains.
• The second category would be the types of stablecoins that are being proposed by some large investment banks. These are envisaged for use in more mainstream financial- or corporate-sector uses, including treasury payments and cross-border payments. The assets backing these coins might conceivably be deposits at central banks.
• Third, the proposed Facebook-led stablecoin, Diem, is an example of a stablecoin that would be aimed at retail use. For households or merchants using Diem coins in everyday transfers and payments, the system would have many of the attributes of a stored-value facility (SVF) or ‘e-money’, and the particular ledger technology behind it would probably not be important to users.