The main difference between a winch and a hoist is the braking system. Most offroad winches are made with dynamic brakes, meaning that the gear system is designed to automatically hold the load. A dynamic brake uses the gears in the winch to provide resistance, acting as a brake. But with this type of braking system, the winch line could bleed out slightly under a heavy enough load. Dynamic braking is not safe for suspended loads. If you try using your winch as a hoist, the load could slip, creating a danger hazard, or the gears could strip out, damaging the winch.
A hoist, on the other hand, includes a mechanical braking system, which is a physical brake that locks the spool in place so that there is no line bleed. In addition, there is no freespool mechanism available on a hoist.
Some specially-manufactured winches are designed to double as a hoist. In order for these devices to act as a hoist, the device must include a locking brake and no freespool mechanism (or the freespool must be completely removed or disabled). Never use a winch as a hoist unless the manufacturer specifically states that the winch is approved for use as a hoist.