While the i3 supports hw-accelerated transcoding/streaming, it’s a super early version. The iGPU only got better / usable for Plex with Kaby Lake – so I don’t think you’re getting some decent hw-accelerated streaming from that CPU/iGPU.
As for the PassMark score…
the i3 should have an avg. score a little below 1800 points.
the Xeon should give you approx. 6300 points
Therefore… while the i3 might have been able to deal with a single 720p transcode, the Xeon should be able to deal with up to three 1080p transcodes.