Outside the United States, cider usually refers to a fermented, alcoholic beverage. It's what Americans call hard cider. But within the US, the distinction between apple cider and juice isn't always clear.
When most of us think of apple cider, we probably picture an opaque, highly perishable apple drink available at farm stands and markets in the autumn. It's juice, but unfiltered and sometimes unpasteurized. In unpasteurized apple cider, naturally occurring yeasts can cause fermentation, making the drink slightly fizzy and alcoholic over time.
Some states spell out a distinct difference between apple cider and juice. For example, the Massachusetts Department of Agricultural Resources specifies that "Fresh cider is raw apple juice that has not undergone a filtration process to remove coarse particles of pulp or sediment .... Apple juice is juice that has been filtered to remove solids and pasteurized so that it will stay fresh longer."
In other places, apple cider refers to juice made from apples picked early in the season. Then there are companies like Martinelli's that use the terms solely as marketing. On their website, they admit their clear, shelf-stable "apple juice and cider are the same; the only difference is the label .... some consumers simply prefer the traditional name for apple juice."
What's the difference in your mind? Do you prefer one or the other?