A380 why wingtip fence and not winglet

[hekokimushi]

Hi guys

i would like to know why the A388 does not use winglets but use wingtip fence just like A320. any one got any reference or explanation?

how does winglet differ from wingtip fence?

[Another DMI]

If wing any longer there woud be even fewer airports that could handle the aircraft due taxi way clearance & gates.