Gnome Standard is the default UI. To change it, click the gear-like icon during your first login and choose "classic" instead of "standard":
For more information about Gnome Classic and Gnome Standard please check the following articles
Gnome Standard or "Gnome Shell"
See for more information https://wiki.gnome.org/Projects/GnomeShell/Tour
The default look and feel appears like this
You can click on "Activities" to search for applications, get the menu and have an "Exposé-like" view of all windows
Gnome Classic
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See for more information
https://help.gnome.org/users/gnome-help/stable/gnome-classic.html.en
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As you can see, "Gnome Classic" is more similar to the Windows or the KDE experience of OpenSuSE Leap 42