In the old days when I was still involved in Ethereum Classic, it had a complete standalone VM, an independent core protocol codebase, and developers who primarily worked on the Ethereum Classic blockchain to drive it forward.
Today on the contrary, it relies heavily on helping hands from developers who primarily work on #Ethereum, massive forking of codebase, and "interoperability". It even trades its principles (immutability / code-is-law) for this.
Probably the most significant change of #Ethereum and Ethereum Classic relation is that it's of a much less hot topic to talk about ETC in #Ethereum. As someone involved in both sides lately I do see the reasons -- ETC is just much less of a threat, so nothing hurts any more to cooperate.