In survival:

My animals I gather and bred despawn every other time I log in. 
This includes the animals I have put name tags on. 
My armor and the armor stands disappear. 
The paintings I create do not drop if broken. 
The villagers disappear and the villages become ghost towns. 

I have lost a full set of enchanted diamond armor. 

In creative:

The animals and villagers that I spawn disappear, even with name tags.