These two glands are found in the skin and are known as exocrine glands because they have a duct through which the substance travels.
If they do not have a duct and secrete a substance directly...
No. Sebaceous glands produce a grease-like substance called sebum which is excreted onto the skin. They are why you get greasy if you get too far from a shower for a couple of days.
It's a modified sweat gland. Milk is essentially modified sweat, which is produced by mammary glands. Sebaceous glands produce sebum, which is this oily substance designed to lubricate skin and hair....
Sweat glands are usually either merocrine (most common) or apocrine (a specialized merocrine gland usually found around armpits that may be responsible for body odor and potentially human pheromones).