Thanks for reading closely, and for flagging this! While CEA is the owner of EA.org, the intro essay was drafted by a collaborative process including non-CEA staff, and the final version was written by 80k’s Ben Todd (more in the essay’s announcement here).
The discrepancy is tracking the reality that there is no consensus about how best to define EA, although I think the omission of collaborative spirit from the CEA page is an oversight and I expect we will edit it accordingly soon.
Quick followup to note that collaborative spirit is included among CEA’s Guiding Principles listed on the CEA site. Clearly it’s confusing—including to a member of CEA’s own staff like me! - that we refer to different things as ‘principles’ in different places, and that might be something we look to clarify if and when we revisit these pages as Zach Era CEA.