Do the following all work and mean the same thing?
1-1. He is a veteran in personal computers.
1-2. He is an expert in personal computers.
2-1. He is a veteran in personal computing.
2-2. He is an expert in personal computing.
No- veteran means he has done it for a long time. An expert could have learned quickly, so one refers to time and the other to knowledge. Personal computers are the machines and computing using them, so an expert in personal computers would be the guy I'd call to fix the machine. An expert in computing could be an expert in software, etc.