Germany's next coronavirus contact tracking app will trigger alerts only if users have a positive result for Covid-19.
This puts you at odds with the NHS application, which relies on self-diagnosis by users through a questionnaire on the screen.
UK health chiefs said the questionnaire is one of the main reasons they are adopting a "centralized" design, despite activists' protests for privacy.
Germany abandoned this model in April.
And on Wednesday, Chancellor Angela Merkel said there would be a "much higher level of acceptance" for a decentralized approach, designed to offer a greater degree of anonymity.
Automated contact tracking uses smartphones to record when their owners are nearby for a significant period of time.
If it is later discovered that someone has the virus, a warning can be sent to others who may be infected, telling them to get tested and possibly quarantined.
In the centralized model, contact matching takes place on a remote computer server.
And the UK's National Cybersecurity Center said it would allow capture attackers trying to abuse the self-diagnosis system.
On the other hand, the decentralized version performs the process on the phones themselves.
And there is no central database that can be used to re-identify individuals and reveal who they spent time with.
BBC News technology correspondent Rory Cellan-Jones said: "The NHS is betting heavily on alerting app users when they have contact with someone who has only reported symptoms.
"This can make the application fast and effective – or it could mean that users are exasperated by a storm of false alarms."
Merkel said that SAP and Deutsche Telekom – which are developing the app from Germany – were waiting for Google and Apple to launch a software interface before they could complete their work.
And BBC News learned that the two U.S. tech companies plan to release the final version of their API (application programming interface) on Thursday.
Details of Germany's Corona-Warn-App published on the code-sharing site Github they say it depends only on medical test results to "prevent misuse".
Those who obtain positive results will receive a verification code that must be entered into the app before anonymously flagging them as being a risk to others.
Germany led the tests in Europe and currently has the capacity to analyze about 838,000 samples per week.
O The UK is reaching – but the scientists who advise the NHS say they can save more lives by using self-diagnosis data as well.
"Speed is essential," said Christophe Fraser of the Oxford Big Data Institute last week.
It may take several days to obtain the results of the Covid-19 test.
And the reported symptoms can be triggered instantly.
But an ethics advisory board advising Health Secretary Matt Hancock about the app has warned many resulting "False positive alerts can undermine trust in the app and cause undue stress to users."
The NHS is currently testing its application on the Isle of Wight.
But a Health Department spokeswoman said that was expected.
"In a matter of days, more than 50,000 people downloaded the app with extremely positive feedback," she told BBC News.
"But, as with all new technologies, there will be problems that need to be resolved in the way it works, which is why it is being tested before the national launch."
The NHS is also exploring the use of the Apple-Google API, which would imply a shift to the decentralized model.
But he plans to offer users the centralized version first, unless plans to complete the implementation in fifteen days go wrong.
A point of contention may be the need to limits on how data is used – possibly demanding a new law.
This would avoid the risk of a repeat of the situation in Norway, where the local data protection body has accused the country's health authority of not performing an adequate risk assessment of a centralized contact tracking application.