The Update Manager now groups packages together according to their source package. A line no longer represents a single package but a software update which consists in one or several packages.
When a developer fixes a bug or writes new features, the source code is modified and all packages which are related to it become available under a new version. It is therefore futile and sometimes dangerous to apply some package updates and not others within the same source package.
In the screenshot below, the Update Manager shows 10 software updates. These updates represent a total of 70 packages. The LibreOffice update is selected and the Update Manager shows the 22 packages it contains. At the bottom of the screen, the Mesa update contains 18 packages, some of which are known to break your system if you were to apply them individually.