Revision r45 typically includes the latest versions of Google Play Services and the Play Store available at the time of the build. This saves the user from having to download massive updates immediately after flashing the ROM.
However, BiTGApps is not just another GApps package; it is built on a specific philosophy of minimalism and performance. While other packages (like the now-dormant OpenGApps) focus on offering a "full suite" of apps, BiTGApps focuses on providing only the essentials. bitgapps-arm-12.0.0-r45