Can you answer this NSFW potentially gross obscene question?

They are only both “similar” in that they are hormonal secretions from mammals.

But milk (any milk, not just human milk) is a protein solution mixed with fat and sugar (lactose), ideal nutrition for consumption by infants.

Semen has fluids from a number of glands, and is filled (in most cases) with sperm. And it does have sugar (glucose) to keep sperm fed and motile. But that’s about it. Not very nutritious for humans.

Also, a human breast can produce 8 to 12 ounces of milk consistently many times during the day. You would have a hard time getting more than a couple tablespoons of ejaculate from a
man under the age of 25 in a single day.