"Biodegradable" is a broad term. It does not tell you where the material breaks down, how long it takes, or under what conditions.
"Compostable" should refer to a defined environment and a recognized test or certification pathway. Industrial composting and home composting are also different conditions.
A good product claim should answer:
- Is it industrially compostable or home compostable?
- Is the finished product certified?
- Are suitable facilities available?
- Is the item accepted with the waste it contains?
- Does the certification cover the ink, adhesive, thickness, and final construction?
Without those details, the claim is not very useful to the consumer.