Although all of the above options focus on similar objectives in blockchain technology such as improved scalability, interoperability, and reduced costs, there is a reason why sharding is considered a layer 1 solution or a solution that is incorporated into a blockchain protocol itself.
Sharding: Imagine a giant book where everyone writes down their transactions. Sharding is like dividing that book into smaller, manageable parts, each handled by a different group of people. Each group, or shard, processes its transactions. Sharding is a big change to the book itself, making it more efficient.
Rollups: You write down most of the details in a separate notebook, but you keep a summary in the big book. This way, the big book doesn't get too crowded, and it's faster to read.
State Channels: Imagine talking to a friend privately without writing anything in the book. You only update the book when you finish your conversation. It's like having private chats without everyone seeing them in the book.
Sidechains: It's like having a different book (a sidebook) for certain types of transactions. You can do some transactions in this sidebook, which is connected to the main book. It helps keep the main book less cluttered.
So, sharding changes the big book itself to make it faster and more efficient. Rollups, state channels, and sidechains are like tricks or tools you use to work with the big book without changing it much. They all aim to make transactions quicker and cheaper but in different ways.
