Endocrine glands: The glands which secrete hormones and other substances directly into the bloodstream are called endocrine glands. Eg. Pituitary, Pineal, Thyroid, Thymus, Gonads, etc.
Exocrine glands: The glands which secrete substances on the epithelial surface through the ducts are called exocrine glands. Eg. sweat, salivary, mammary, ceruminous, lacrimal, sebaceous, prostate, and mucous glands.