Summary:
Unlike Java, in Bedrock you cannot place hanging signs on these blocks:

• Anvil (use command)
• Door
• Chorus Flower
• Spawner
• Grindstone
• Daylight Sensor
• Stonecutter
• Turtle Egg‌
• Shulker Box

Also in Bedrock you can place a hanging sign on the vertical sides of Farmland and Dirt Path. In Java, you cannot place hanging signs on the vertical sides of Farmland and Dirt Path since these sides are not complete.

Steps to reproduce:

1. Place the blocks indicated in the list in the air.
2. Try to place hanging signs as shown in the screenshot (see in attached).
   ---> You cannot place a hanging sign.
3. Place Farmland and Dirt Path.
4. Place the hanging signs on the vertical sides of Farmland and Dirt Path.
   ---> You can place a hanging sign.

Observed results:
The placement of blocks does not correspond to Java.

Expected results:
The placement of blocks corresponds to Java.

Screenshots:
Java

Bedrock