Collapsed Core = Core+Distribution
but still we have CE in collapsed core.
Ref: https://www.google.co.in/imgres?imgurl=http%3A%2F%2Fwww.ciscopress.com%2Fcontent%2Fimages%2Fchap1_9781587133329%2FelementLinks%2F01fig08.jpg&imgrefurl=http%3A%2F%2Fwww.ciscopress.com%2Farticles%2Farticle.asp%3Fp%3D2202410%26seqNum%3D4&docid=vaqHHkPVZmMeAM&tbnid=p64V2Yd2gvG28M%3A&w=360&h=284&bih=667&biw=1360&ved=0ahUKEwjdk6717_TMAhXB3KYKHcQEDEcQMwgdKAEwAQ&iact=mrc&uact=8
http://www.ciscopress.com/articles/article.asp?p=2202410&seqNum=4
Check: Figure 1-8 Two-Tier Hierarchical Design