I frequently see one of these used when the other is required.

Problem:
These two sentences do not mean the same thing.

Explanation:
The sentence “It tastes different.” means that “It” has a different taste than something else.

In other words, “It tastes different.” effectively is an abbreviated sentence for something like “It tastes different than ice cream.”

The sentence “It tastes differently.” means that “It” now tastes things differently than it formerly tasted things.

The source of the confusion between using the adjective “different” and the adverb “differently” is due to the fact that the verb “taste” has definitions when used with an object and other definitions when used without an object.

• The most common definition of the verb “taste” with an object is to test the flavor of [the object] by putting some in the mouth or on the tongue;
• The most common definition of the verb “taste” without an object is to have a particular flavor.

Solution:
Use “It tastes different.” when referring to the taste of something. Use “It tastes differently.” when referring to the ability of something to test the flavor of other things.