Hmm. Almost nothing... Source codes were opened from the very beginning as for BTC & for XMR. It's not a difference...

Two independend teams (Cryptonote & XMR) did academical work on prove strict anonimity by design.

G. Maxwell, core Bitcoin dev, did not hide his interest in Cryptonote technology and wrote scepticism about coinbase-like mixing approaches, used in DRK & XC.

Cryptonote team made challenge to all, by not just open the source code, but by make forked Cryptonote coins easy in few step-by-step instructions.

P.S. Bloating is not so terrible, 1.3 to 1.5 Gb in a month, note exchange volume of XMR is greater than other coins. 1Tb HDD are cheaper and cheaper every single day.

Disadvantage, XMR can not stake coins in Android/iOS wallet, as XC can. Also it's PoW, CryptoNight is very hard for ASICs, a lot harder than X11 algo.