Largely the difference is in your ability to transport alcohol. In all but 7 states, open container laws typically do not permitted one to have open containers of alcoholic beverages in a vehicle and having such can be evidence of a DUI or DWI in and of itself. The idea is that the open container can be used by the driver who was pulled over, and in the time, it takes the cops to walk from their car to the suspects, the driver can pass the open container to a friend and claim it was the friend who was drinking, not the driver.
Generally, "open containers" will be considered such if there is no possible means of closing the container (Think your typical "Red Solo Cups") such that liquid cannot escape if the container is turned upside down. A previously un-corked and re-corked bottle of wine would be less suspicious, especially if the driver and passengers cannot regularly access it.
Specifically, the law makes it illegal to have an open container in the passenger compartment. If you intend to transport an opened container, it's advised to place it in the trunk space of the vehicle though there can be some trouble if your trunk has no separation from the passenger compartment (i.e. In a van or SUV where the cargo space is accessible behind the back seat of the vehicle). It also excuses vehicles that are driven commercially for human transport (so Buses, Limos, and Taxis), many of which have a separation of the driver and passenger compartments. Additionally, the vehicle must be being driven at the time of the offense AND on a public right of way (so tailgating does not fall under this, since the vehicle is parked, often in a privately owned parking lot).
When not dealing with vehicles, open carry laws are usually to prevent drinking on publicly owned property, so you cannot drink while you are walking on a sidewalk. Usually this is a local ordinance, and not a state law.
In all cases, "Open containers" legally imply an intent to drink, whereas closed containers legally imply no intent to drink. As such, any minor (legally defined as Under 18 years of age, occasionally under 21 when dealing with alcohol laws) is not allowed to possess an open container with few exceptions (typically letting a minor drink on rare occasions such as holidays OR for religious ceremonies such as Sacramental Wine in various sects of Christianity).