Prior to this, such a synchronisation was restricted by the Apple OS’, forcing users to alternate between the two services. On that note, getting both accounts synced up simply requires Apple users to start up Google Photos and going into the app’s settings. With the latest version of the app, you should see a new option that turns on the synchronisation.
The function should be instant and once turned on, you can and should be able to begin syncing your liked photos on Google Photos with Apple Photos, and vice versa. Do note that, at current, the reverse process is slightly slower, with Google Photos taking approximately a minute or two longer to sync liked images from Apple Photos. (Source: Google Photos via Android Police)
