_id versus id

I noticed that gets require the _id not the id field. For example

http://east.gluu.org/api/v1/art/530e334845a8840b20368947

returns this object:

{ "_id" : { "$oid" : "530e334845a8840b20368947" }, "medium" : "fashion", "description" : "Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.", "buyURL" : "http://ebay.com/item/WxVsfapS4H8=\n", "sold_out" : true, "year" : "2014", "id" : "160d7fed-8409-405c-8de4-d4c7b44fef02", "size" : "63 x 30", "artist" : "82ed7279-a2d9-4a44-b59b-72532e466be4", "title" : "Austin Skyline", "venue" : { "phone_number" : "1-512-837-5043", "status" : "active", "picture" : "http://aloft.gluu.org//men/person2.jpg", "twitter" : "@smartiepossible", "preferred_contact" : "email", "address" : { "country" : "US", "region" : "TX", "postal_code" : "78702", "street_address" : "5305 Bolm Rd, #12.2", "locality" : "Austin" }, "id" : "82ed7279-a2d9-4a44-b59b-72532e466be4", "family_name" : "Manning", "sub" : "smartiepossible", "role" : [ "artist" ], "given_name" : "Elijah", "_id" : { "$oid" : "530e334645a8840b203685b0" }, "email" : "smartiepossible@gmail.com" }, "alt_urls" : { "Detail" : "http://www.agedendeavors.co/S/CoWw==" } }

I am trying to figure out how to align this...

- Mike