There are many types of fence on the market; and each one serves to protect gardens against a specific animal. Deer fencing itself is a broad term. A deer fence does not just protect plants against deer damage, but can also be used against coyotes, wolves, foxes, rabbits and groundhogs (if using a metal deer fence, of course). However, some fast-moving critters, such as squirrels, and birds will need a fence that includes a top. 

A deer fence will simply not do for these types of animals that climb, or swoop down, over fences. Squirrels, opossums and other types of animals will require a garden fence enclosure to block all climbing attempts, and aerial attacks, from all sides of the enclosure.