Hi! I also asked this question way back 1 month ago or 2 if I am not mistaken and I think I still have their answer.

"ERC 1400 token is a cryptotoken built on Ethereum blockchain. It differs from other tokens built on ETH (ERC-20, ERC-777), because of special requirements for Security tokens.

Accelerate the issuance and management of securities on the Ethereum blockchain by specifying a standard interface through which security tokens can be operated on and interrogated by all relevant parties.

Security tokens differ materially from other token use-cases, with more complex interactions between off-chain and on-chain actors, and considerable regulatory scrutiny.

Security tokens should be able to represent any asset class, be issued and managed across any jurisdiction, and comply with the associated regulatory restrictions."