The Zynq device on the 7015 PicoZed Module is the XC7Z015-1CLG485. The XC7Z015 is not offered in the SBG485 package, which is what the ZC7Z030 uses. These devices are footprint compatible, as explained in Chapter 6 of http://www.xilinx.com/support/documentation/user_guides/ug933-Zynq-7000-PCB.pdf.
There are some references in the PicoZed documentation that imply that the XC7Z015 uses the SBG485 package. This is not correct, and we are working on correcting these now to avoid any confusion. The XC7Z015 on PicoZed uses the CLG485 package.