Oversetterens betraktninger:

There is a shade of difference between ‘conservation area’ and ‘protected area’.

For example, in the UK a conservation area is defined thus:

Conservation area designation introduces a general control over the demolition of unlisted buildings and provides a basis for planning policies whose objective is to conserve all aspects of character or appearance, including landscape and public spaces, that define an area’s special interest.

The International Union for Conservation of Nature (IUCN) has this definition of a protected area:

A protected area is a clearly defined geographical space, recognised, dedicated and managed, through legal or other effective means, to achieve the long term conservation of nature with associated ecosystem services and cultural values. (IUCN Definition 2008)

Therefore I would say that a protected area is a natural environment, such as those listed above, while the term ‘conservation area’ is broader and covers various built environments.