Just a wild guess here - Android development may mean modified stock ROM and Original development may mean ground up or based on AOSP.
Android Development topics include ROMs that are a modified version of someone's official port of an existing ROM. For example, CyanogenMod - if you take the original ROM for our ZR and make some minor changes (add your own theme, change the /system directory a bit, etc.), then that topic, and your ROM, goes in the Android Development.
If your ROM has been created from scratch (ground up, as you'd say), or represents a port of an existing ROM for our phone (like Miui) that didn't exist beforehand, then your ROM belongs in the Original Android Development, and you have full rights to deny or allow permission to use your ROM for other people's developing purposes. The OP decides whether people can use their ROM for tweaking/theming/adjusting needs.
I hope I made myself clear. Cheers!
---------- Post added at 07:44 PM ---------- Previous post was at 07:39 PM ----------
what rom would you recommend to flash in this moment to daily use?
Hi, I would recommend keeping Sony's stock ROM - the 4.4.4 one, mostly because there's nothing wrong with it.
If you're interested in having CM 12 or 12.1, then go ahead and flash that ROM, but those ROMs aren't really awesome in terms of covering everything that your phone can actually have as a feature.
Stock ROMs are much more interesting, and you can still modify the system and do whatever you want with it. I know this mostly because I had CM 12 on my previous phone, Xperia M, and I've missed the stock ROM so much, only because of how nice the Home launcher, the Messaging app, the Stamina feature, the Weather widget, and the Quick Launch Camera feature were.