It is definitely harder to gain significant amounts of experience in PVP. I believe that experience gain is based off of your contributions in battle, so if you have a lower level character that isn't doing as much damage, you likely wouldn't get nearly as much experience as you would with a higher level VR character. I would recommend using siege weapons to increase your experience gain in PVP at lower levels. If you're certain you aren't getting any experience when you should, though, you might want to submit a bug report.