Other Sample: clicking on a link may load the page is 1 second, sometimes 5 seconds or even it might take 10 seconds to load it completely. It depends on various factors such as the application server response time, network bandwidth , client system capabilities.

Synchronisation is for example if we login a facebook through an android mobile it will ask whether to sychronise the contacts that is merge the contacts in fb with whatsapp. This is called as synchronising.Here what we need to test is we have to test whether both the datas or apps merge with each other and once we stop synchronising it should gets stopped and both should work as separate apps

http://www.tutorialspoint.com/qtp/qtp_synchronization.htm