1. **Different Materials**: Some soccer balls may be made of rubber, while others may be soft plastic or inflatable. These different materials provide dogs with varying sensations and textures when biting and playing.

2. **Different Sizes**: Some soccer balls may be smaller, suitable for small dogs to bite and chase, while others may be larger, suitable for larger dogs. The difference in size also affects the comfort and excitement of dogs during play.

3. **Different Shapes**: Some soccer balls may be standard round shapes, while others may have special shapes such as oval or irregular shapes. Different shapes of soccer balls trigger different interests and play styles in dogs.

Overall, providing dogs with different styles of soccer balls can enrich their playing experience, allowing them to enjoy a variety of fun activities.