The biggest advantages of XC4000X devices are significantly increased system speed, greater capacity, and new architectural features, particularly Select-RAM memory. The XC4000X devices also offer many new routing features, including special high-speed clock buffers that can be used to capture input data with minimal delay.

Any XC4000E device is pinout- and bitstream-compatible with the corresponding XC4000 device. An existing XC4000 bitstream can be used to program an XC4000E device. However, since the XC4000E includes many new features, an XC4000E bitstream cannot be loaded into an XC4000 device.

The XC4000X Series devices are not bitstream-compatible with equivalent array size devices in the XC4000 or XC4000E families. However, equivalent array size devices, such as the XC4025, XC4025E, XC4028EX, and XC4028XL, are pinout-compatible.