Worlddestroyed

Hello Mojang Team,
I Have a big problem,
when i put my MC world(v1.7-1.7.10) and drag it into the 1.8 snapshot(all versions) then my world is ok,
but when i take this world and put that back to a version of 1.7,

• the itemframes fall downfrom the wall,
• inventory get clear,
• flowers in pots will deleted,
• and more,
  in one version it was so terible that all trees was away.
  my question, is that a bug and mojang fix it in the future or give it alternative where the worlds dont destroyed
  pls help
  Thanks mojang Team
  ps iam german so my english is not so good