A testnet is a blockchain that is still being developed but is open to software writers so they can experiment with their own programs. A testnet allows software writers to check that their code runs properly before they make possibly costly deployments to a mainnet; this works for both seasoned blockchain developers as well as students looking to polish their skills. It also gives an opportunity for everyone to give feedback about the performance of the platform. A testnet environment provides the virtual machine, a blockchain and a faucet for test tokens so that the developer has everything they need for the testing and verification of their use cases, avoiding the mainnet and the use of real cryptocurrency for their tests.
What is an Emulator?
An emulator is a program that reproduces the functions or actions of a different computer, operating system or other software. In this case, it is web-based software that enables you to execute programs as if they were running on the Cardano blockchain, though it does not simulate all aspects of the blockchain.