Exocrine glands secrete substances such as enzymes, hormones, and sweat onto an epithelial surface, usually through a duct. Examples of exocrine glands include sweat glands, salivary glands, mammary glands, and oil glands.
Endocrine glands secrete hormones directly into the bloodstream. These hormones are then transported around the body to regulate various processes. Examples of endocrine glands include the pituitary gland, thyroid gland, and adrenal glands.