From your description above, it sounds like what your professor is calling a multi-factor authenticator would be a system like a Chip and PIN terminal for credit cards, where the user must first insert their chip, then enter their PIN. The client terminal passes the PIN to the card, which then uses the PIN along with a secret key stored inside the chip to produce a single cryptographic message to be delivered to the bank's host computer. The bank's host cryptographically verifies that the correct PIN was used with the Chip, and so they authenticate the transaction which authorizes the transfer of your money to the store.
A multiple single-factor-authenticator would be a system where you are presented with two screens: enter your PIN, then enter the value from the token you carry in your pocket. Or enter your PIN, and press your thumb on the reader. The two factors are unrelated at the client end of the transaction; both are independently verified by the host system. The host does not validate the transaction until both authenticators are independently verified.
What your description is glossing over is that a Chip in a "multi-factor authenticator" Chip and PIN system is actually capable of performing a single factor authentication right there on site, without the benefit of the host system. Entering a wrong PIN will cause the Chip to refuse to communicate. Entering three wrong PINs and the Chip will lock out the user until the card is reset by the bank. So there are still two independent authentications, PIN to Chip (local), and Chip to bank (remote). But only one (stealing the PIN) can be stolen by an attacker.
The primary difference is that the Chip is a local representative of the Bank. It's like having a tiny banker in your pocket. Your bank doesn't trust the terminal, it doesn't trust you, it only trusts their tiny banker. So your communication with the Chip is single factor authentication (the PIN). The Chip uses both your PIN and its internal secret to authenticate you to the bank in a single message. In this system, the bank barely has to trust the terminal at all. The terminal can even be compromised: imagine using your Chip card at a store run by a thief, where his evil terminal copies your PIN and your card number. But just knowing your PIN and card number is not enough to steal from your account - the bank won't authorize on PIN and card number, they only authorize their Chip's message and card number. And your Chip will only talk to the bank while it's in the reader. Take the Chip out, and it's secure again.
The multiple single-factor-authenticator would be two separate messages. A thief's store could steal your PIN, and then steal the number you entered that was displayed on your token. Or they could steal your PIN and make a copy of your thumbprint. The attacker could then replay those messages to authenticate themselves as you to a different host. In this case, all trust exists in any system that can intercept both messages.
There have been other commercial systems that turned multiple single-factor-authenticators into multi-factor authenticators in hardware. A few years ago a company marketed a thumb reader/PIN pad device, where the user entered a PIN and pressed their thumb on a screen. Note that while a thumbprint can be copied, and a PIN can be copied, the device combined the PIN and a "hash" of the thumbprint with a cryptographic algorithm (based on a secret key embedded in the reader) and sent a single authentication message to the host. So someone intercepting the message could recover neither the PIN nor the thumbprint from the message. A thief could still present a fake thumbprint to a reader, however; and a reader could be a fake that steals the full image of the thumbprint and the PIN, but these are attributes of the factors, not of the system.