Everything below is relevant for web3.js v1.x.
There is no such function
There is function
The difference is that function
web3.eth.accounts.create() merely returns an object with an account credentials, while
web3.eth.personal.newAccount() creates an actual account on the node, via an RPC (remote-procedure call) to a node process (e.g., Parity, Geth, Ganache, etc).
Due to the above, function
create is synchronous by nature and returns the result immediately, while function
newAccount is asynchronous by nature and returns a
Promise object which must be resolved (waited for) in order to obtain the result.
So you will technically be doing:
const accountObject = web3.eth.accounts.create(...);
const accountAddress = await web3.eth.personal.newAccount(...);
Here is the official documentation: