There's no hard and fast delineation between standard binos and marine binos, but the difference is in magnification and the size of the objective lenses. Standard binoculars have a typical ratio of magnification:objective of 4-5x. Think about an 8x40 (5x) or 10x40 (4x) and similar sizes as examples of standard binoculars. Marine binoculars have a higher ratio, often 6-8x. An example of a common marine bino spec would be a 7x50, with 7x magnification and a 50mm pair of objective lenses.
The lower magnification helps minimize image shakiness on rolling seas, while the larger objective provides a brighter picture on dark nights and also provides a larger exit pupil size for long-duration viewing comfort and reduced eye strain, particularly in low-light situations. As horse1 mentioned, marine binos often include a built-in compass as well. More modern (and expensive) marine binos also include a rangefinder. The larger objective lenses, compass, and rangefinder, however, all add considerable weight. Whether those benefits of marine binos are worth the added price and weight and more limited magnification on dry land is a personal preference.
Personally, I would stick with an 8x40 or 10x40 (or 8x42 or 10x42) for hunting use.
