Depends on the age.
If they are both from the same series and clock speeds, they'll be pretty much the same, only difference is that the Xeon processors can be used with multi processor motherboards.
System Manufacturer/Model Number Built By ELiTEFX 2012 OS Windows 7 Ultimate SP1 x64 CPU Intel Core i7 2700K @ 4.515 Ghz Motherboard ASUS P8P67 Deluxe Memory 16GB GSkill Ripjaws X DDR3-1600 Graphics Card 2 x MSI R6870HAWK 1GB TwinFrozr III CrossFire Enabled Monitor(s) Displays Samsung 27" LED 2ms Syncmaster S27B350 Screen Resolution 1920 x 1080
Keyboard Logitech G510 Mouse Razer DeathAdder PSU Corsair TX850W Case Coolermaster CM690 Cooling Coolermaster V8 Hard Drives Mushkin Chronos MKNSSDCR120GB SSD 550/515 MB/sec
Seagate ST31000528AS 1TB HDD
Seagate ST31000528AS 1TB HDD Internet Speed 18mbps/.512mbps Other Info Samsung SH-S243D DVD+RW/DVD-RW Optical Drive
5x120mm Blue LED Case Fans
Logitech Z4 2.1 80 Watt Sound System
Cisco DPC3008 Docsis 3 Cable Modem
TP-Link TL-WR1043ND Wireless N Gigabit Router