As stated publicly by the BIS (central bank that governs all other central banks) in the top comment of the referenced thread, the difference with CBDCs would be granularity of targeting, in real-time, at the transactional level.
As to the question of "why bother", one stated reason for CBDCs is to enable nation-state competition with Facebook's Diem cryptocurrency, whose stated reason for existence is to compete with Bitcoin, whose observed reason for existence is to make a small subset of humans more wealthy.
There are also incentives for non-government entities, https://bariweiss.substack.com/p/get-ready-for-the-no-buy-li...
> First, in January, PayPal blocked a Christian crowdfunding site that raised money to bring demonstrators to Washington on January 6. Then, in February, PayPal announced that it was working with the Southern Poverty Law Center (SPLC) to ban users from the platform. This week the company announced it is partnering with the Anti-Defamation League (ADL) to investigate and shut down accounts that the ADL considers too extreme.