Struggling with inventory space, but trying to keep Stormblood gear sets for glamour, I've noticed most of it are recolors of old gear, and dublicates can be safely discarded to make place for more unique models or for new dyeble versions. So far my findings are:

Weapons
Lv60 i255 crafted are recolors of Lv60 i150 crafted weapons
Lv61 i260 Ghost Barque sets are dyeble recolors of i148 Thavnairian weapons from The Great Gubal Library
Lv62 i265 crafted are recolors of Lv50 i70 crafted weapons
Lv63 i270 Ruby Tide and Lv70 i300 Crimson Lotus weapons share the same model, both are not dyeble and have different colors, so you can pick just one version you prefer
Lv64 i273 crafted are non-dyeble versions of Lv60 i250 crafted weapons
Lv65 i276 - these are recolors of different old sets, for example The Crying Wind is recolor of i90 Elfin Bow
Lv66 i279 crafted are recolors of Lv57 i142 Halonic and Lv51 i120 Martial weapons
Lv67 i282 Doma Castle weapons are non-dyeble versions of i180 Hunt Seals weapons (which are dyeble)
Lv68 i285 crafted = new models?
Lv69 i288 = new set

Armor
Lv60 i255 crafted is dyeble version of i215 dungeon sets
Lv61 i260 Ghost Barque sets are dyble recolors of i215 dungeon gear but with jobs switched around, for example DRG gets wooden mask which was previously caster exclusive
Lv62 i265 crafted set is dyeble version of i160 Valerian set
Lv63 i270 Shisui set = new
Lv64 i273 crafted is dyble version of i195 Dravanian set which was also recolor of Lv55 i136 Orthodox set
Lv65 i276 Nomad set = new
Lv66 i279 crafted = new set
Lv67 i282 Yanxian set is non-dyeble version of i180 Asuran set (can be purchased for Hunt seals)
Lv68 i285 crafted = new set
Lv69 i288 Valerian set (not to confuse with i160 Valerian) = new set

If you have any corrections or addittions please add ^^