Pink gear is Aetherial gear which is looted from dungeons. It is only slightly better than white which is normal gear. Green is scarce, which usually means that it has a higher ilvl than gear lvl.
Actually you've reversed that: both are usually 1/2 iLVLs higher than the required level. However Pink/Aetherial has the potential to be stronger depending on your luck.
The difference is that the stats for Green are pre-determined and unchanging. Every single 44 Coliseum Shawl, for example, will always have the exact same stats and will never change (barring any patch itemization changes). However, an equivalent 44 Aetherial DoW chest piece maybe have STR and VIT static and up to 1-3 additional stats that are randomly generated.
Brayflox's Longstop is a prime example of this because you usually get a lot of Aetherial/Pink pieces from the non-boss chests. Sometimes you'll find a say a WHM Cane that has 2-3 stats on it; another time it may have 4-5.