It's depend on the consensus and how does it design. The interval value could be defined based on the calculated result and the capacity of network.
E.g: You defined the interval between block is ~ 2 secs, you might need to calculate following these thing:
Time for major nodes to reach an agreement to choose the next minter
A window of time for another ...
They are not interchangeable but often are used interchangeably incorrectly as they are very similar.
A consensus protocol is actually a combination of at least 2 rules:
A block author rule
A chain selection rule
ETH 1 and BTC use Proof-of-Work combined with the Longest Chain rule to reach whats called Nakamoto Consensus. Proof-of-Work is often incorrectly ...