I am starting to learn about blockchain. After reading about the main concepts composing a blockchain network, I have some doubts that I am not able to solve despite performing many searches on the internet.
On the one hand, it is clear that transactions are grouped into blocks and the miner node that solve the consensus algorithm is the one putting the block in the distributed ledger. However, I have read that Ethereum (usually used for cryptocurrency with Ether) could be used as blockchain platform for different applications such as food traceability, assets management, etc. In this case, all these applications are using the same distributed ledger, i mean, the Ethereum distribution ledger can store different kinds of blocks, i.e. blocks from a food traceability application, from the assets management one or those derived from cryptocurrency?
On the other hand, I understand the role of smart contracts but it is not too clear for me which is the difference among the consensus and contract layer and when smart contracts are needed.
Could you help me with these doubts?
Thank you in advance for your help