What’s special about each of these sentences?

Easy:

1. A bad chef, mad like a jackal, made a damaged, half-baked milk cake a mile high.

2. Tomorrow we’ll see pretty yellow buttercups scattered across sunny green hills.

3. Your woozy son stoops to put your toy ox up onto your toy zoo.

Hard:

1. A beefy chimp hops by, almost billowy in his loopy effort.

2. A nightclub academic stayed late, off dancing with Miami DJ funk.

What’s special about each of these sentences? It's different for each sentence.

Easy:

1. A bad chef, mad like a jackal, made a damaged, half-baked milk cake a mile high.

2. Tomorrow we’ll see pretty yellow buttercups scattered across sunny green hills.

3. Your woozy son stoops to put your toy ox up onto your toy zoo.

Hard:

1. A beefy chimp hops by, almost billowy in his loopy effort.

2. A nightclub academic stayed late, off dancing with Miami DJ funk.