The Xeon are an i7 without a igpu. So they have unlocked Hyperthreading. That means basically they are like an 8 core version of the 4 core i5s. In single thread heavy games like skyrim or fallout, this doesn't do anything, these games use 1-3 cores at best. But in multiple core games like BF4 it's a rather large advantage. With steam games, streaming, etc using compressed audio to make dls smaller, cpu cores are being utilized to uncompress that audio, so all 8 threads of an fx or i7 get used. You can do a lot more work with 8 threads at 3.3GHz than 4 threads at 4.8GHz. It's a lesson learned from consoles like the ps4 which uses an 8 core fx cpu at 1.8GHz. They have to fit that whole game on a limited Blu-ray, and that includes the compressed audio. It equates to higher fps as 4 or more cores can be dedicated to the game graphics and data leaving 4 cores working the audio, Windows, other pc stuff. With an i5, you cut that working in half. This is going to be the trend with most AAA games that run at bf4's level of complexity. It's the same trend as happened a few years ago, between dual core cpus and quad core. Gta: V min required is a quad core (there's a hack for the pentium g3258) and the g3258 suffers even with a good OC, it just doesn't have the core count to work all that data without bottlenecking.
A Xeon / i7 gets the same performance as an i5 in single thread games, but the i5 is lacking in multi-thread. It's going to be a better choice in upcoming titles.
So a Xeon is an i7 with no internal graphics. Not that big a problem for any gamer, those with FX Cpus have been dealing with that for years. But it is also a locked multiplier cpu just like any other non-k Intel cpu. Just has 8 threads to work with instead of four, at the same price as the 4 core cpus.