There is supposed to be full character customization, but I can't confirm any details since customization wasn't enabled in the open beta.
However this customization has been taken way too far and while traditional uniforms and equipment is available, there's also lots of (IMO) stupid stuff like pilot helmets, leather jackets, prostetic limbs, blue face paint, Asian women fighting in the British army, Allied soldier with a katana on his back, etc. Besides completely ruining immersion it's basically impossible to tell who on earth you ran into and in the beta I basically could only tell the teams apart at first glance because friendlies have a 3D HUD icon above them and enemies don't.
Vehicles will also be customizable with upgrades changing their appearance (long barrel or side skirts for the Panzer IV for example) and with cosmetic items such as flags, mascots, camo nets, improvised armor such as sandbags, etc.