iMessage on laptop vs. iPhone

[iMore Question]

Why would the message notification on my boyfriend's Mac differ from the ones on his phone? He thinks it has to do with being logged in, but if he is logged in the Mac still shows x number of messages more than his phone. I think it might be the difference between threads deleted on phone vs laptop, but I can't find any literature or backing to that. Thanks for any input.

 

[Just_Me_D]

You're probably right in regard to thread deletions, being that iMessages aren't necessarily synced between devices.