When you are in Survival Mode and your Inventory is full and you use /give to give you Items, there will be dropped in front of you. But if you have enough space to pick these dropped Items up you are not able to pick them up. It doesn't matter if you try to pick these items up in survival mode or in creative mode, these items can't be picked up.

Demonstration: https://youtu.be/jy6vb86QhhY