The mechanics, step by step
The wholesaler signs an agreement of purchase and sale with an assignment clause, markets the contract (not the property) to end buyers, and assigns it for a fee before the original closing date — the seller closes directly with the end buyer, not the wholesaler.
Where it goes wrong, legally and reputationally
A wholesaler who doesn't disclose the assignment to the seller, or who ties up a property with no real intent or ability to close if no assignment is found, is the pattern that gives the strategy a bad name and creates real legal exposure.
How this differs from what a direct buyer does
A direct buyer (like a fix-and-flip investor) closes and takes title personally; a wholesaler never takes title at all — the distinction matters for a seller trying to understand who they're actually dealing with.