An endocrine gland is a gland that secretes hormones directly into the bloodstream. These hormones are chemical messengers that help control metabolic processes throughout the body. Examples of endocrine glands include the pituitary gland, thyroid gland, and adrenal glands.
An exocrine gland is a gland that secretes chemical substances, such as enzymes and hormones, into a duct that leads directly to the outside of the body. Examples of exocrine glands include sweat glands, sebaceous glands and salivary glands.