Entitlement is the full set of government approvals you need before you can legally build the specific building you drew. Zoning is one piece of that. If a parcel is zoned for multifamily, the code allows apartments there in principle, but you still normally need site plan approval, a subdivision or lot line change, utility and sewer capacity sign-off, stormwater approval, sometimes a design review, sometimes a traffic study, and then building permits. A site can be perfectly zoned and still have no approved plan attached to it.
So the person who told you zoning and entitlement aren't the same thing was right. "Entitled" in strict usage means the discretionary approvals are done and you can move to permits. Loose market usage is broader, and you'll hear people call a site "entitled" when they just mean zoning is favorable. When a seller says it, ask exactly which approvals are in hand and get copies.
Two years and six figures is normal in a slower jurisdiction, and it can be much faster in a permissive one. What varies is the number of public hearings, and that varies by state and by city, so the only useful answer comes from the planning department that governs your parcel.
One thing worth knowing early: most experienced buyers don't pay cash for unentitled dirt. They tie it up with a long option or a contract with entitlement contingencies, so if the approvals die the land goes back to the seller and their loss is the soft costs rather than the whole purchase price.
