differ about

differ (with someone) about something

 and differ (with someone) on something 
1. [for someone] to disagree with someone about something. I must differ with you about that. We differ about that. I don't differ with you on that point.
2. [for someone] to argue with someone about something. Tom was differing with Terry rather loudly about which one of them was going to carry the flag. Let's stop differing with each other on these simple things!
See also: differ