I can't list them for your, because there have been 170+ releases of Bitcoin Core, (what you perceive currently as "original"). See them here, and you can check the release notes for each and every version available.

Apart from the 2000+ closed issues in bitcoin core's github, you can see all the BIPs (Bitcoin Improvement Proposals), some of which have been implemented (either partly or in full) here.

You can't expect a piece of software to stay the same for that long, no matter how big/small, popular/unpopular it is. If it's being used, it changes. It's been 8 years since bitcoin started. Even Microsoft's Windows has major changes (a.k.a. Service Packs, or more recently "Updates" [in the vein of "Creator's Update" etc]) within the same version.

Bitcoin's Github repository has, while writing this, 14,597 commits (each commit may fix a bug or insert a new feature, or remove a deprecated feature, or a combination of them -among others, this is an oversimplified list-)

So, in that way, the "original" bitcoin doesn't exist, since a long time ago. There have been at least 13 public major releases (0.2 being the first I can find in the repository linked above, and 0.14 being the current) that bring new functionality, many more bugfixes (0.14.2 is the current) and even more release candidates, which are what we call "almost ready for production" packages.

Segwit2 is an improvement proposal from the current bitcoin team (Bitcoin Core, aka "official client"), and Bitcoin Cash (the "unofficial fork") was trying to push some other changes. The result is that the community is now split in 2, and that's why the fork will happen tomorrow. They both are direct descendants from the "original" bitcoin, which stopped existing since v0.2 (and we now are on v0.14).

I'm sorry I wrote such a big comment. It was either this or no comment at all. I don't like half-assing information.

I'm linking for you here, the release notes from v0.14.2, scroll down to "0.14.2 Change log" (located about half-way), and read the changes for the second revision of v0.14.