What is the difference between glands and enzymes?
The difference between these structures is considerable.
Glands are anatomic features of animals, generally internal ones, which are identified by the tissues they are composed of and the role they perform. Glands are differentiated from other organs in that their qualifying feature is the ability to produce and release substances within the body. These substances include mucus, hormones, oils and sweat. Glands are categorized as a characteristic of the endocrine system, which is responsible for regulating homeostasis and helping the body communicate with itself via the release of the aforementioned substances.
Enzymes are a completely different thing, almost to the point that the two have little if anything directly to do with each other by points of comparison. Enzymes are a type of protein molecule which catalyze a reaction, mostly due to being shaped and charged so that they have a very specific set of conditions for what they interact with, and therefore what reaction they catalyze. Enzymes are also exponentially smaller than glands. What they do have in common is that some glands, such as the pancreas and liver, secrete enzymes as one of their products.