Reuters:

In Europe, most countries have chosen short-range Bluetooth “handshakes” between mobile devices as the best way of registering a potential contact, even though it does not provide location data.

But they have disagreed about whether to log such contacts on individual devices or on a central server – which would be more directly useful to existing contact tracing teams that work phones and knock on doors to warn those who may be at risk.

Related note (via this MacRumors post):

Apple and Google are now referring to “contact tracing” as “exposure notification,” which the companies believe better describes the functionality of their upcoming API. The system is intended to notify a person of potential exposure, augmenting broader contact tracing efforts that public health authorities are undertaking.

See also the embedded Exposure Notification FAQ from the Apple/Google team. Can’t help but wonder if the name change from contact tracing to exposure notification was an attempt to ease EU concerns about privacy.